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Genetic Diversity in Major Farm Crops on the Farm and in Reserve
Abstract
Genetic vulnerability does not at this time present a major threat to production of United States field crops, according to
a 1981 survey of U.S. crop breeding directors. But plant breeders do regard genetic vulnerability as an important and potentially
dangerous problem. The 1981 survey indicated that although the genetic base of U.S. field crop production is not as narrow
as in 1970, it still is concentrated on a relatively small number of favored cultivars. Genetic diversity is provided, nevertheless,
in other and less obvious ways. Survey responses indicated that the genetic base of the elite germplasm pool is wider and
provides more useful diversity than is usually supposed. However, breeders also value the national germplasm repositories
as indispensable sources of needed diversity.
... В последние десятилетия все большее внимание уделяется описанию и сохранению генетического разнообразия. Главные его источники, по мнению ряда ученых [26][27][28][29], сосредоточены в местных сортах и популяциях, сохраняемых в коллекциях генбанков. Изучение местных сортов может не только дать полную картину генетического разнообразия культурного вида, которое в сортах современной селекции весьма ограничено, но и позволить выявить генотипы, интересные в качестве доноров редких аллелей генов хозяйственно значимых признаков. ...
... .26. ...
... Рис.9.26. Дендрограмма генетического подобия сортов льна, различного происхождения и селекционной направленности, построенная по результатам SSR-анализа: I -сорта льна-долгунца, IIсорта льна масличного. ...
... However, the relatively narrow gene pool (Heath and Hebblethwaite 1985) and the heavy use of a small number of varieties as parents by competing breeding programs have led to low genetic diversity among pea cultivars (Singh, 1990;Simioniuc et al., 2002;Baranger et al., 2004). Extensive use of closely related cultivars by producers could result in vulnerability to pests and diseases (Duvick, 1984;Cox et al., 1986). Previous (Smelcerovic et al. 2006 andVerma et al. 2008). ...
... This showed that there was variability for various traits. A wide range of variation was noticed for plant height (24.5-33 cm) in KMPR594, while for internode distance (4.5-6cm) in KMPR569, number of nodes (5)(6)(7)(8) in KMPR526, number of leaves (9-12) in KMPR594, number of branches (5)(6)(7)(8) in KPMR583, length of branch from main axis (1.2-2.6cm) and stem circumference (1.1-12cm) in KMPR526 as shown in ( (Table 3). The greatest value of mean was found for radicle length (4.39) in KPMR526, The present study revealed the genetic diversity within a collection of pea germplasm representing different geographical regions of India, using molecular (RAPD) approaches. ...
... This showed that there was variability for various traits. A wide range of variation was noticed for plant height (24.5-33 cm) in KMPR594, while for internode distance (4.5-6cm) in KMPR569, number of nodes (5)(6)(7)(8) in KMPR526, number of leaves (9-12) in KMPR594, number of branches (5)(6)(7)(8) in KPMR583, length of branch from main axis (1.2-2.6cm) and stem circumference (1.1-12cm) in KMPR526 as shown in ( (Table 3). The greatest value of mean was found for radicle length (4.39) in KPMR526, The present study revealed the genetic diversity within a collection of pea germplasm representing different geographical regions of India, using molecular (RAPD) approaches. ...
Analysis of the extent and distribution of genetic diversity in crop plants is essential for optimizing sampling and breeding strategies. Germplasm characterization and evaluation yield information for more efficient utilization of these valuable resources. Morphological characters and Randomly amplified polymorphic DNA (RAPD) was used to estimate diversity among 5 genotypes of Pea (Pisum sativum). Selected four RAPD primers generated 24 bands, 10 of which were found to be polymorphic. All the primers produced polymorphic amplification products, however the extent of polymorphism varied with each primer .The percentage of polymorphism generated by primer was P-03 (83.33%), P-05 (25%), P-06 (16.66%) and P-17 (50%). Great variation among morphological characters viz., plant height, number of nodes, internode distance, number of branches, length of branch from main axis, number of leaves, stem diameter, germination percentage and radicle length was observed. UPGMA (Unweighted Pair Group Method with Arithmetic Mean) dendrogram obtained from cluster analysis using Jaccard's similarity coefficient resulted into two major clusters. Cluster I comprised of two genotypes KPMR526 and KPMR569; Cluster II can be further divided into two sub clusters, Sub cluster I comprised two genotypes KPMR571 and KPMR583 while as sub cluster II consists of a single genotype KPMR594. All the genotypes could be discriminated from one another using combined profiles of 4 primers.
... In the last two-three decades, there has been a plethora of studies reporting the general decline of agricultural biodiversity across the globe (Duvick, 1984;Vellve, 1993;Tripp, 1996;Khoury et al. 2022;Fu 2006Fu , 2015Mir et al. 2012;Brush 1999;Brush et al. 1992;Hammer and Teklu 2008, but also see Montenegro de Wit 2016). A broad consensus is that the traditional landraces in the elds of farmers were largely replaced by modern or improved cultivars; so on-farm conservation of landraces has been greatly compromised (Brush et al. 1992;Teklu and Hammer 2006;Witcombe et al. 2011;Wood and Lenne 1997). ...
... In traditional agroecosystems, genetically heterogenous crop landraces have been cultivated in an assemblage of di erent crop species in a temporally and spatially diverse crop arrangement or cropping pattern; they are mostly managed with low externally procured inputs and family labor (Jarvis et al., 2008;Koohafkan and Altieri, 2011;Zeven, 2002). This is in stark contrast with the vast swathes of modern crop elds performing monocultures of 'modern cultivars' developed through government-or private-funded projects and disseminated by private players or agricultural extension programs and supplemented with heavy inputs, i.e., agrochemicals, water, or power-driven machinery (Duvick, 1984;Zhu et al., 2000). The imminent question arises: how did it happen? ...
The rapid and expansive decline of agrobiodiversity has become a global concern now. With the new research pouring in, the description of the problem, its scale and magnitude has been well documented and analyzed. So are suggested mitigation measures that include ex situ or in situ conservation measures. However, oftentimes the causal processes promoting the decline are equated with the general loss of biodiversity or developmental programs like the Green Revolution. While their negative impacts cannot be ruled out, the question of the decline deserves deeper examination. And, it should embrace the larger political ecological context that has been embedded in the historical development of crop breeding and improvement leading to global agrarian change. Though kick-started later in India, the crop improvement programs instrumental over decades also brought in irreversible decline in agricultural biodiversity. The aim of this chapter is to uncover the general processual developments in crop improvement programs and their effects on agricultural biodiversity.
To do so, I analyze the country-wide situation by citing examples from various crops and taking their improvement history into account. It reveals that the release of improved cultivars and their gross acceptance followed by the dwindling of traditional varieties has led to gradual homogenization. For many crop species, just a few improved cultivars began to hold a significant percentage of acreage. Although it was pioneered by the Green Revolution cereals, rice and wheat, the decline of diversity and wider acceptance of only a few cultivars have been pervasive across crops, cereals and non-cereals alike. Cotton display yet another example of decline that has been rooted in historical processes. The recent invasion of GM cotton and other biofortified crops are the newer avenues of probable decline. Analyses also suggest that the productivity gain or yield increase has been the prime mover behind the improvement programs. I also delineate the implication of the decline for food security. It emphasize the impending threats from disease or pest susceptibility that may endanger global agriculture. It also recognizes the impacts of the general decline in diversity on changes in food and nutrition, loss of cultural diversity of food, and growing corporate power in agriculture. In conclusion, a set of mitigation measures through community mobilizations, and social institutions have been discussed; and a few complementary policy formulations have been recommended.
... The various features of rice like availability of saturated molecular markers, smallest genome, precise genome sequence, diploid, self pollinating crop make it extensively studied among cereals and model crop for genetic studies. Molecular Marker based Genetic Diversity Analysis (MMGDA) also has potential for evaluating changes in genetic diversity over time and space (Duvick 1984) [5] . Numerous molecular markers are being used for fingerprinting and diversity analysis among crop plants such as Restriction Fragment Length Polymorphism (RFLP) (Sun et al. 2001) [25] , Random Amplified Polymorphic DNA (RAPD) (Williams et al. 1990) [31] , microsatellites or Simple Sequence Repeats (SSRs) (Gao et al. 2005) [7] and Amplified Fragment Length Polymorphism (AFLP) (Aggarwal et al. 1999) [1] . ...
... The various features of rice like availability of saturated molecular markers, smallest genome, precise genome sequence, diploid, self pollinating crop make it extensively studied among cereals and model crop for genetic studies. Molecular Marker based Genetic Diversity Analysis (MMGDA) also has potential for evaluating changes in genetic diversity over time and space (Duvick 1984) [5] . Numerous molecular markers are being used for fingerprinting and diversity analysis among crop plants such as Restriction Fragment Length Polymorphism (RFLP) (Sun et al. 2001) [25] , Random Amplified Polymorphic DNA (RAPD) (Williams et al. 1990) [31] , microsatellites or Simple Sequence Repeats (SSRs) (Gao et al. 2005) [7] and Amplified Fragment Length Polymorphism (AFLP) (Aggarwal et al. 1999) [1] . ...
Rice is the most important staple food grain of all cereal crops and feeds more than half of the world's population. Assessment of genetic diversity is of utmost important in rice breeding from the perspective of selection, conservation and proper utilization. The present study was undertaken with an objective to assess the genetic diversity among 28 rice cultivars by use of 22 SSR markers. A total of 41 alleles were detected across 28 rice cultivars used. PIC values varied widely among SSR loci tested and it ranged from 0.753 to 0.067, with a mean value of 0.376. The 28 rice cultivars were grouped into two clusters i.e., cluster I and II with dissimilarity coefficient 0.42. Cluster I was sub divided into two minor subgroups IA and IB having 6 and 11 genotypes respectively. IB was further subdivided into minor groups. In similar way, the second main cluster i.e. Cluster II was also sub divided into two minor subgroups that is IIA and IIB having 3 and 8 genotypes respectively. IIB further divided into minor groups. This indicated presence of considerable diversity in the genotypes studied. The most diverse cultivars were HUR4-3 and GSRIR1DQ125-L2-D2.
... The various features of rice like availability of saturated molecular markers, smallest genome, precise genome sequence, diploid, self pollinating crop make it extensively studied among cereals and model crop for genetic studies. Molecular Marker based Genetic Diversity Analysis (MMGDA) also has potential for evaluating changes in genetic diversity over time and space (Duvick 1984) [5] . Numerous molecular markers are being used for fingerprinting and diversity analysis among crop plants such as Restriction Fragment Length Polymorphism (RFLP) (Sun et al. 2001) [25] , Random Amplified Polymorphic DNA (RAPD) (Williams et al. 1990) [31] , microsatellites or Simple Sequence Repeats (SSRs) (Gao et al. 2005) [7] and Amplified Fragment Length Polymorphism (AFLP) (Aggarwal et al. 1999) [1] . ...
... The various features of rice like availability of saturated molecular markers, smallest genome, precise genome sequence, diploid, self pollinating crop make it extensively studied among cereals and model crop for genetic studies. Molecular Marker based Genetic Diversity Analysis (MMGDA) also has potential for evaluating changes in genetic diversity over time and space (Duvick 1984) [5] . Numerous molecular markers are being used for fingerprinting and diversity analysis among crop plants such as Restriction Fragment Length Polymorphism (RFLP) (Sun et al. 2001) [25] , Random Amplified Polymorphic DNA (RAPD) (Williams et al. 1990) [31] , microsatellites or Simple Sequence Repeats (SSRs) (Gao et al. 2005) [7] and Amplified Fragment Length Polymorphism (AFLP) (Aggarwal et al. 1999) [1] . ...
Assessment of variability and trait associations in a crop helps to enhance selection efficiency. With this objective, a study was conducted to estimate the genetic variability, character association and path coefficient analysis for grain yield and its component traits in 80 rice genotypes during Kharif-2020. Eighty genotypes including eight checks were evaluated in alpha lattice design with three replications. For all of the traits studied, the results revealed significant variance in all genotypes.PCV was found to be slightly more than the corresponding GCV for all the characters, indicating the role of environment in the expression of these traits. However, high GCV and high PCV were observed for number of effective tillers, grain yield per plot, number of filled grains per panicle, number of unfilled grains per panicle, biomass yield, harvest index, grain yield per plant and grain yield per hectare. Furthermore, all of the variables investigated had strong heritability and high genetic progress as a percentage of mean, with the exception of days to 50% blooming, days to maturity, and kernel breadth. Days to first flowering, days to 50% flowering, days to maturity, spikelet fertility percentage, number of filled grains per panicle, harvest index and kernel length showed a significant and positive association with grain yield per plot. Highest direct contribution to grain yield per plot was manifested by kernel length, harvest index and spikelet fertility percent. Days to first flowering, days to maturity, number of effective tillers, number of unfilled grains per panicle, test weight, biomass yield were also found to exert a positive effect on yield, thus can be considered as desirable traits for selection in high yielding genotypes.
... Perhaps because modern agriculture relies so heavily on a few crop species, the success of these crops is highly dependent on their genetic biodiversity 4 . Consider some 'Green Revolution' crops, such as rice. ...
... Climate events, especially droughts, have caused 50% of the observed sudden drops in national food production since the Relationship between the national effective crop species diversity and the probability of losing 10%, 15% and up to 25% of national harvest. Using FAOSTAT data, the 91 nations studied in Renard and Tilman 19 were equally divided into fi ve classes of crop diversity (average diversity of each class: 4,6,8,10,15). For all nations in each diversity class, we calculated the probability of harvest loss using the method described 19 . ...
Summry
A confluence of discoveries in ecology and agriculture suggests that biodiversity can help address the sustainability problems facing modern intensive agriculture. Here we explore several questions related to this possibility. Can increases in national crop diversity help increase the stability and security of national food systems? Can practices based on greater crop biodiversity produce yields that compete with those obtained through the long-standing, high-input monoculture model? What are the appropriate levels and combinations of crops to be used? We highlight recent research that suggests it is time to begin unlocking the agricultural potential of biodiversity — from the level of crop genetic diversity to species diversity — and to do so on spatial scales from individual fields to nations. Recent research suggests that the biodiversification of agriculture may lead to greater and more stable yields, decrease land clearing, and lower the use of harmful agrochemicals.
... Breeding progress is a measure of the increase of the offspring's average genetic value for a specific trait compared with the whole population of previous generation's average. One of the methods widely used to estimate the progress made from genetic gain achieved in plant breeding programs is the regression of the average performance of released varieties for a specific trait in different environments over their years of release (Duvick, 1984). This estimation has been used for several major crops, for instance in wheat (Triticum aestivum L.;Peltonen-Sainio and Peltonen, 1994;De Vita et al., 2007;Giunta et al., 2007;Mladenov et al., 2011, Taghouti et al., 2017Laidig et al., 2017b), barley (Hordeum vulgare L.; Laidig et al., 2017a), chickpea (Cicer arietinum L.; Tadesse et al., 2018), common bean (Phaseolus vulgaris L.; Barili and do Vale, 2016), and soybean [Glycine max (L.) Merr.; Tefera et al., 2010]. ...
... Normality tests of data per year and per station were performed for frequency distribution observation prior to further statistical analyses. To estimate the genetic gain from the breeding program, linear regression analysis between varieties' mean yields and their respective years of registration (Duvick, 1984) in both locations ( Jamaât Shaim and Marchouch) was performed. The rates of progress in ...
Lentil (Lens culinaris Medik.) is an important grain legume worldwide. It contributes to sustain farming through its ability to fix N in soils and to enhance human nutrition and health thanks to its nutritionally rich grains. In Morocco, it is consumed as staple food by a large proportion of the population. However, the country depends on importation to meet the national demand at the cost of losing valuable currencies. One of the factors limiting lentil production in Morocco is the availability and use of certified seeds of improved varieties. In this research, we aimed at evaluating genetic gain from breeding, adaptation and stability of available improved varieties to make recommendations aiming to enhance their use and adoption by farmers. We studied 9 registered varieties and two candidate lines in 14 different environments for grain yield. All the tested varieties and candidate lines had higher yield than the actual average yield of lentil in Morocco. Significant increase and higher genetic gain over the local check were observed from 1989 to 2018. Up to 35 kg ha⁻¹ yr⁻¹ genetic gain for grain yield was obtained. The yield advantage of improved varieties over the local check increased from 16 to 67% from 1989 to 2018. Most of varieties have wide adaptation and respond positively to the increase of environmental index. The environmental factor in terms of the amount and distribution of rainfall has a determinant effect on grain yield for all varieties and candidate lines. However, differences in the degree of adaptation and stability of these varieties were observed. These results could help draw more attention to lentil in Morocco and define efficient strategies that make the best varieties available for farmers from the perspective of enhancing national production.
... These surveys seemed to indicate that diversity of the US maize crop might be narrowing (NRC 1972;Zuber and Darrah 1981). However, more positive responses were received about available diversity (Duvick 1984), reflecting the understanding that diversity resides in breeding programs as a whole rather than just the commercial portfolio at any single place and time (Duvick 1984). The optimal way to meaningfully monitor diversity is to apply molecular markers directly to hybrids coupled with information on their relative usage. ...
... These surveys seemed to indicate that diversity of the US maize crop might be narrowing (NRC 1972;Zuber and Darrah 1981). However, more positive responses were received about available diversity (Duvick 1984), reflecting the understanding that diversity resides in breeding programs as a whole rather than just the commercial portfolio at any single place and time (Duvick 1984). The optimal way to meaningfully monitor diversity is to apply molecular markers directly to hybrids coupled with information on their relative usage. ...
Maize has for many decades been both one of the most important crops worldwide and one of the primary genetic model organisms. More recently, maize breeding has been impacted by rapid technological advances in sequencing and genotyping technology, transformation including genome editing, doubled haploid technology, parallelled by progress in data sciences and the development of novel breeding approaches utilizing genomic information. Herein, we report on past, current and future developments relevant for maize breeding with regard to (1) genome analysis, (2) germplasm diversity characterization and utilization, (3) manipulation of genetic diversity by transformation and genome editing, (4) inbred line development and hybrid seed production, (5) understanding and prediction of hybrid performance, (6) breeding methodology and (7) synthesis of opportunities and challenges for future maize breeding.
... The impacts of modern plant breeding on crop genetic diversity has been a major concern of many scientists in search for implementing efficient conservation strategies and a better utilization of germplasms (see Duvick, 1984;Fu, 2007Fu, , 2015 for review). In particular, some temporal patterns of genetic diversity have been observed (Rauf et al., 2010;van de Wouw et al., 2010b,c). ...
... In particular, some temporal patterns of genetic diversity have been observed (Rauf et al., 2010;van de Wouw et al., 2010b,c). The high selection pressure in modern plant breeding has reduced crops genetic diversity over time (Duvick, 1984;Hallauer and Darrah, 1985;Bowman, 2003;Gepts, 2006;Fu and Dong, 2015). In particular, allelic reduction at specific loci and allele loss over time have been reported in the Canadian hard red spring wheat germplasm (Fu et al., 2005). ...
Durum wheat was introduced in the southern prairies of western Canada in the late nineteenth century. Breeding efforts have mainly focused on improving quality traits to meet the pasta industry demands. For this study, 192 durum wheat lines were genotyped using the Illumina 90K Infinium iSelect assay, and resulted in a total of 14,324 polymorphic SNPs. Genetic diversity changed over time, declining during the first 20 years of breeding in Canada, then increased in the late 1980s and early 1990s. We scanned the genome for signatures of selection, using the total variance Fst-based outlier detection method (Lositan), the hierarchical island model (Arlequin) and the Bayesian genome scan method (BayeScan). A total of 407 outliers were identified and clustered into 84 LD-based haplotype loci, spanning all 14 chromosomes of the durum wheat genome. The association analysis detected 54 haplotype loci, of which 39% contained markers with a complete reversal of allelic state. This tendency to fixation of favorable alleles corroborates the success of the Canadian durum wheat breeding programs over time. Twenty-one haplotype loci were associated with multiple traits. In particular, hap_4B_1 explained 20.6, 17.9 and 16.6% of the phenotypic variance of pigment loss, pasta b∗ and dough extensibility, respectively. The locus hap_2B_9 explained 15.9 and 17.8% of the variation of protein content and protein loss, respectively. All these pleiotropic haplotype loci offer breeders the unique opportunity for further improving multiple traits, facilitating marker-assisted selection in durum wheat, and could help in identifying genes as functional annotations of the wheat genome become available.
... Analysis has the potential for assessing changes in genetic diversity over time and space (Duwick, 1984). DNA markers are predominantly used in molecular characterization and diversity studies due to their abundance and repeatability . ...
... Genetic diversity is generally measured by genetic distance or genetic similarity, which imply that there are either differences or similarities at the genetic level of the plant [23]. Molecular marker based Genetic Diversity Analysis (MMGDA) also has potential for assessing changes in genetic diversity over time and space [24]. As the variation among the genotypes comes from the variations in DNA sequence, therefore, variations in DNA sequence are the basis of genetic diversity analysis [25]. ...
Genetic Diversity and Population Structure of Boro Rice Landraces of
Bangladesh
Mohammad Khalequzzaman1
, Mohammad Zahidul Islam2
*, Md. Ferdous Rezwan Khan Prince3
, Ebna Syod Md. Harunur Rashid4
and Md.
Abubakar Siddique5
1Bangladesh Rice Research Institute (BRRI), Gazipur-1701, Bangladesh
2Bangladesh Rice Research Institute (BRRI), Regional Station, Goplalganj, Bangladesh
3Genetic Resources and Seed Division, Bangladesh Rice Research Institute (BRRI), Gazipur-1701, Bangladesh
Abstract
Molecular characterization, evaluation of genetic diversity and assessment of relationship by simple sequence
repeat (SSR) markers of 48 Bangladeshi Boro rice landraces was performed. Among the total 58 SSR markers, 55
markers has been distributing over 12 rice chromosomes showed clear polymorphic band patterns, and they were
selected for genetic relationship assessment. A total of 228 alleles were detected with an average of 4.15 alleles per
locus. The average values of gene diversity and polymorphic information content (PIC) were 0.39 and 0.36, respectively.
Primer RM206 had the highest PIC value (0.78) and the highest number of alleles (10).Therefore, RM206 was detected
for the highest level of polymorphism and RM206 is supposed to be the best marker for characterizing the 48 Boro rice
landraces. The genetic distance-based results in the unrooted neighbor-joining (NJ) tree revealed four (4) major clusters
(I,II,III and IV)and a model-based population structure analysis generated two clusters (A and B). Both neighbors joining
tree analysis and the population structure analysis method showed the tested landraces as highly diverse in structure.
The two and three dimensional graphical views of Principal Coordinate Analysis (PCoA) revealed that the landraces
Mi-Pajang, Gopal Beshi, Borail, Madhabsail, Boro (sunga) and Jala Boro were found far away and distributed around
the centroid of the cluster. This rice collection and information gained in this study will be useful for future rice breeding
program.
Molecular markers are the powerful tool
... In fact, genetic erosion due to scientific selection is neither inevitable, nor necessarily the most probable outcome in farmers' fields. Duvick (16) noted two countervailing forces regarding crop diversity. On the one hand is the substantial economic gains to be had from the lower unit costs of food production, processing, and consumption that come from uniformity in particular phenotypic traits in certain cropping systems (e.g., uniform crop emergence, flowering and harvesting times; plant, seed, or fruit size, shape or composition; and so on). ...
A prevalent and persistent biodiversity concern is that modern cropping systems lead to an erosion in crop genetic diversity. Although certain trait uniformity provides advantages in crop management and marketing, farmers facing risks from change in climate, pests, and markets are also incentivized to adopt new varieties to address complex and spatially variable genetics, environment, and crop management interactions to optimize crop performance. In this study, we applied phylogenetically blind and phylogenetically informed diversity metrics to reveal significant increases in both the spatial and temporal diversity of the US wheat crop over the past century. Contrary to commonly held perceptions on the negative impact of modern cropping systems on crop genetic diversity, our results demonstrated a win-win outcome where the widespread uptake of scientifically selected varieties increased both crop production and crop diversity.
... Molecular characterization provides a precise tool for estimation of genetic diversity and germplasm identi cation. Molecular marker based genetic diversity analysis has the potential for assessing the changes in genetic diversity over time and space [39]. In the present study, a total of 15 markers (12 SSR markers and 3 gene based markers) distributed throughout 12 rice chromosomes were used to assess the genetic diversity across 48 rice genotypes (40 advanced breeding lines and 8 cultivated varieties). ...
Background
Rice breeders stand at the forefront for application and advancement in breeding and genome based marker system for more realistic and applicable strategies in order to create opportunities for sustainable utilization of genetically diverse rice resources. In Kashmir rice cultivation is under diverse environmental conditions that is encountered by selection pressures of environmental heterogeneity, biotic and abiotic stresses, however competent enough to provide good yields, whereby drawing the attention of the breeder. Therefore, tremendous genetic differentiation and diversity has occurred at various agro-ecosystems.
Methods and Results
This study is a pioneering effort where agro-morphological and SSR markers has been employed to assess the genetic diversity and genetic structure of advanced rice breeding lines and local collections from northern Himalayan region of India along with screening for disease resistance. In the present investigation, a total of 15markers (12 polymorphic SSR markers and three gene specific markers) were used for agro-morphological characterization and genetic differentiation of 48 rice genotypes (40 advanced breeding lines and eight cultivated varieties). The genotypes were evaluated under two environments; Khudwani (E1) and Wadura (E2) during Kharif 2020. Results based on agro-morphological and cooking quality traits revealed that 48 genotypes got grouped into seven clusters with KS11 and KS7 at the extremes. The cluster I was the largest comprising of 13 genotypes followed by cluster III (11 genotypes), cluster II and cluster IV had 9 genotypes each. ANOVA also revealed significant mean squares for the genotypes under study with respect to all the traits in two environments (E1and E2). From principal component analysis (PCA) only six principal components (PCs) exhibited more than 1.00 Eigen value and explained 71.44 % cumulative variability among the traits studied. The result from the calculation of SSR molecular marker was further verified with clustering analysis, genetic diversity parameters, AMOVA, phenotypic characterization and validation based on gene specific marker analysis. The cluster analysis revealed wide genetic variability among the 48 genotypes with Cluster III comprises of 19 genotypes, Cluster I with 17 genotypes, whereas cluster II comprised of 12 genotypes. The genetic profiles detected 53 alleles from these 15 loci, with PIC values of 0.494 per locus. Based on AMOVA, variation was distributed within population 99% and among populations no significant genetic differentiation was observed. The average number of effective alleles (Ne) was 1.38 with higher effective alleles in Population-1 (1.52) than Population-2 (1.24). Based on phenotypic characterization, most of genotypes along with two resistant checks (DHMAS and Shalimar Rice-1) displayed resistant reaction, followed by 16 genotypes showing moderately resistant while two landraces viz., Mushk Budji and Red Rice proved highly susceptible. Out of 48, three and nine genotypes were positive for gene Pikm with respect to marker Ckm-2 and dominant marker Pikh-STS, respectively. Moreover, this low level differentiation among sub-species could provide an opportunity to identify the gene combination well-adapted by natural selection.
Conclusion
The pattern of clustering based on SSR markers provided information about shared genetic characters among rice genotypes in order to eliminate duplications between rice genotypes. Such a genetic differentiation within genotypes provides an insight towards selective pressure and evolution adaptation to local conditions and could be utilized for introgression of resistant gene for higher yield potential, and development of rice varieties with better plant types as per the preferences of rice consumers.
... Morphological and biochemical markers tend to be restricted to relatively few traits, display a low degree of polymorphism, are often environmentally variable in their manifestation and depend on the expression of several unlinked genes (Melchinger et al. 1991). In contrast, molecular marker-based genetic diversity analysis has potential for assessing changes in genetic diversity over time and space (Duwick 1984). Molecular markers have been extensively used in characterization of plant genetic resources. ...
Study of genetic relationships is a prerequisite for plant breeding activities as well as for conservation of genetic resources. In the present study, genetic diversity among and within 15 Iranian native Ajowan (Carum copticum L.) populations were determined using inter simple sequence repeat (ISSR) markers. Twelve selected primers produced 153 discernible bands, with 93 (60.78%) being polymorphic, indicating considerable genetic diversity at the population level. Number of polymorphic bands per primer ranged from 4 to 11 with an average of 7.75. The largest percentage of polymorphic loci was 78.57% for primer UBC818. Based on an un-weighted pair-group method using arithmetic average (UPGMA) clustering algorithm, four distinct groups were established. Results of the principal coordinate analysis (PCoA) corresponded to those obtained through cluster analysis. Analysis of molecular variance (AMOVA) showed that the genetic variation was found mainly within populations (61%), but variance among populations was only 39%. This study has detected significant genetic differentiation among C. copticum populations. The current study confirmed the importance of molecular studies in detecting genetic variation among genotypes in selecting diverse parents to carry out crossing program successfully.
... Despite successful collection and conservation of crop diversity, the use in crop improvement did not commensurate with the efforts spent on collection and conservation. This has been a global phenomenon as Duvick (1984) reported the use of only around 1.5% of the total collections in the USA (across crops), and the same is true for India. This must change with the generation of more and more information about the potential value of collected crop diversity to promote greater use in genetic improvement of crop species for increasing productivity. ...
India is rich in biological diversity, being one of the 17 mega-biodiverse countries in the world. It has an amazing range of habitats available in its 10 + 1 bio-geographic zones (Singh 2017a, b), habiting about 20,141 taxa of higher plants (angiosperms) with 17,926 species belonging to 2991 genera and 251 families, representing approximately 7% of the described higher plant species in the world (Karthikeyan 2009). As per archaeological evidence, the Indian Subcontinent has played an important role in the origin and evolution of agriculture from the hunters-gatherers stage to domiculture and to settled agriculture exploiting both flora and fauna. These efforts led to the evolution of the Indus Valley Civilization developed and flourished nearly 5000 years ago (3300–1300 BCE; mature period 2600–1900 BCE), Vedic Civilization (1500–500 BCE), Mahajanapada (600–400 BCE), etc., as gleaned from the findings of numerous archaeological sites across the country. Recent studies have shown that the process of origin and evolution of agriculture predominantly occurred at 21 agricultural biodiversity heritage sites, spread over the subcontinent with domestication, adaption, and cultivation of many crop species suited to diverse ecologies offered by the subcontinent (Singh 2015). These fell parallel to 21 agro-ecological zones, identified for the subcontinent (Sehgal et al. 1992) with a rich diversity of crops and genetic diversity in adapted crop species (Fig. 11.1), throughout ecological zones and beyond, under more than 120 production systems. Significant progress has been made in the collection, characterization, conservation, and utilization of crop diversity in crop improvement. However, there remain gaps needing new approaches for effective management and sustainable use, including bioinformatics, genomics and molecular breeding, and engineering cultigens meeting the emerging challenges.
... Traditional breeding is potential candidate genes and their transformation by a labor-intensive approach that was first employed to conventional genetic engineering techniques to increase increase yield and create plants that could thrive in abiotic stress tolerance [34]. specific growth situations [25]. Breeding involves creating different QTL combinations and choosing the most Enhancing Plant Herbicide Resistance: Crop plants promising ones to use in further breeding [26]. ...
The importance of optimal nutrition for human health and development is well recognized. Crop yields are more impacted by adverse environmental factors than by pests and diseases, such as drought, flooding, excessive heat and so forth. Finding methods to maintain high productivity under stress and developing crops with improved nutritional value are therefore two primary objectives of plant scientists. In order to satisfy the global need for high-quality foods, genetically modified crops may show to be effective complements to those made using traditional techniques. Genetically modified crops can be utilized to raise yields and nutritional quality as well as their tolerance to a variety of biotic and abiotic challenges. There have been some biosafety and health concerns raised in relation to genetically modified crops, but there is no reason to be worried about consuming products that have undergone rigorous development and thorough testing. The objective of achieving food security for both the present and future generations can be accomplished by integrating modern biotechnology with conventional agricultural practices in a sustainable manner. To fulfill the task of feeding the expanding global population, climate change adaptable crops must be developed. By inserting nucleic acid molecules produced by any method outside the cell into any virus, bacterial plasmid, or another vector system to enable their incorporation into a host organism in which they do not naturally occur but in which they are capable of continued propagation, genetic modification refers to the creation of new combinations of heritable material. One of the most common and controversial results of modern biotechnology is genetically engineered organisms. Recombinant DNA technology progress had followed the emergence of genetic mechanisms and biological variability. Recombinant DNA is produced synthetically by combining two or more DNA molecules into a single molecule. By increasing yield and reducing reliance on chemical pesticides and herbicides, genetically modified foods have the potential to address many of the world's hunger and malnutrition issues as well as contribute to environmental conservation and maintenance. Genetically modified plants can help commercial agriculture overcome a number of present problems. One of the most dynamic and innovative worldwide industries, the current market trends project benefits consumers, major national economies and growers as well.
... No caso do milho, 71% da área, então cultivada, era ocupada por cultivares derivadas de apenas seis linhagens, o que levou à conclusão de que a produção agrícola americana era vulnerável geneticamente (NATIONAL ACADEMY OF SCIENCES, 1972). A vulnerabilidade genética do milho foi estudada posteriormente por Duvick (1984), que constatou que a base genética do milho cultivado nos Estados Unidos foi ampliada em comparação ao levantamento efetuado na década de 1970, porém a produção ainda se baseava em um pequeno número de cultivares. ...
A grande diversidade genética do milho faz com que ele seja cultivado em quase todo globo terrestre e utilizado de inúmeras formas. A alta tecnificação empregada no cultivo do milho engloba o uso de cultivares produtivas e uniformes em detrimento às cultivares tradicionais que guardam entre si maior diversidade genética. Com a tecnificação do cultivo do milho, a preservação dos recursos genéticos do milho em condições ex situ tornou-se prevalente a sua preservação in situ/on farm. As coleções de germoplasma de milho mantidas ex situ têm diversas funções e finalidades, entre elas, a coleção base visa a preservação a longo prazo; a coleção ativa, também chamada banco ativo de germoplasma de milho que visa a preservação a médio prazo, ambas, preservam variedades locais ou exóticas e cultivares obsoletas. Ações de conservação, agregação de valor e promoção do uso de acessos preservados em bancos de germoplasma por meio da conservação on farm ou do melhoramento devem ser desenvolvidas de forma conjunta para atingir a adequada preservação de recursos genéticos, permitir o seu uso e ainda para permitir que variedades tradicionais voltem a sofrer pressão de seleção em campo possibilitando, desta forma, a evolução destas variedades e da cultura. O objetivo desse trabalho foi rever os recursos genéticos de milho desde a origem deste cereal até o uso da sua biodiversidade em programas de melhoramento com ênfase nas atividades desenvolvidas no âmbito do banco ativo de germoplasma de milho no Brasil preservado na Embrapa Milho e Sorgo em condições ex situ.
... The use and improvement of diverse genetic resources is not often a priority within private breeding programs. Public breeding programs provide genetic diversity in reserve (Duvick 1984), breeding creativity, and an insurance against genetic vulnerability through continuous genetic improvement of elite genetically broad-based breeding populations (Carena and Wicks III 2006). Exotic germplasm includes genetic materials not presently adapted to target environments lacking immediate usefulness without adaptation and improvement (Carena and Hallauer 2001a). ...
... One 386 way to minimize the effects of salt and anaerobic 387 stress on plant growth and yield is through the 388 introduction of species/varieties capable of 389 tolerating soil salinity and waterlogging. Simul-390 taneously appropriate strategies for integrated (Duvick 1984;FAO 2010). This is more perti- (Table 4). ...
In the coastal and humid tropical island region, waterlogging and soil salinity are serious threat to the sustainability of rainfed agriculture due to sea water inundation and intensive monsoon rainfall. In addition, there has been a marked change in surface temperature, rainfall, evaporation, and extreme events linked to climate change affecting the tropical islands. Therefore, an innovative management of waterlogged and saline soils of island ecosystem is imperative for sustainable agricultural production. The current technology enables the transfer of desirable genes from wild relatives to cultivated plants and improvement of land races followed by selection of crops and their varieties by the island farming community for waterlogged and saline conditions. The available evidences suggests that crop planning, multistress crop combinations, integrated farming system, and suitable agroforestry models have the potential to provide the basic needs of the people even under stressful and climate change situations. Land shaping measures have great potential to address waterlogged and salinity together while it promotes crop and farming system diversification which are more sustainable than monocropping with rice. In island conditions, rain water harvesting, storage, and its efficient use should be an integral part of the strategy for sustainable agricultural production. In addition, the livelihood of the people can be enhanced by suitable aquacultural practices in the coastal saline soils while sea weed cultivation holds greater promise to diversify the agricultural activities in the island saline environment.
... Сокращение генетического разнообразия сельскохозяйственных культур делает их более уязвимыми к болезням и насекомым, а в долгосрочной перспективе, ставит под угрозу возможность устойчивого генетического улучшения. Поэтому в последние десятилетия в мире все большее внимание уделяется описанию и сохранению генетического разнообразия.Главные его источники, по мнению ряда ученых [1,[3][4][5], сосредоточены в местных сортах и популяциях, сохраняемых теперь только в коллекциях генбанков. Изучение ландрас может не только дать полную картину генетического разнообразия культурного вида, которое в сортах современной селекции весьма ограничено, но и позволить выявить генотипы, интересные в качестве доноров редких аллелей генов хозяйственно-значимых признаков.Лен обладает уникальной особенностью, которая проявляется в "пластичности" его генома. ...
В результате ПЦР со специфическими праймерами в
коллекции белорусских ландрас льна (Linum usitatissimum L.) выявлено 14 образцов, несущих стабильно наследуемую однокопийную вставку LIS-1. Данные образцы, предположительно, обладают высокой пластичностью генома, и могут быть полезны для создания высоко-адаптивных сортов льна.
... Assigning the parental lines into different heterotic groups is fundamental for the maximum exploitation of heterosis through hybrid cultivar development in a cross-pollinated crop like maize. Different methodologies have been used to characterize genetic diversity in the maize germplasm, which are morphological characters (Goodman et al., 1977), pedigree analysis (Duvick 1984), heterosis (Smith et al., 1989) and detection of variation at DNA level using markers. Morphological differences are usually determined by a small number of genes and may not be representative of genetic divergence in entire genome (Singh et al., 1999;Brown-Guedira et al., 2000). ...
Information on genetic diversity and relationship among different maize genotypes is very important in hybrid maize breeding program. The purpose of present study was to elucidate the nature and extent of differentiation and divergence among 18 inbred lines of maize based on the analysis of targeted microsatellite sites. Using 28 primer pairs, altogether 296 allelic variants including 145 shared and 151 unique alleles were detected amongst amplified products and a total of 49 loci were assigned with an average of 6.04 alleles per locus. Polymorphic information content of microsatellite primer pairs ranged from 0.34 (umc1304) to 0.93 (umc1179) with mean of 0.77 per primer. A remarkably higher level of genetic differentiation and divergence was revealed by the use of 28 microsatellite markers, which allowed unique genotyping and unambiguous classification of the maize inbred lines under evaluation. Among the inbred lines under molecular characterization, CML163 and CML467 appeared as the most diverse genotypes. Using the matrix of genetic similarity, the cluster analysis grouped the eighteen inbred lines into four heterotic groups. The markers utilized in the present study were sufficient for discrimination and unambiguous classification of inbred lines.
... Several molecular technologies have been used to study the genetic diversity and systematic relationships of Gossypium species (Wendel et al. 1992;Wendel and Brubaker 1993;Abdalla et al. 2001;Iqbal et al. 2001;Gutierrez et al. 2002), and these studies have shown that there is low level of polymorphism within G. hirsutum cultivars. A decline in genetic diversity of G. hirsutum (Upland cotton) cultivars and the need to broaden the genetic base of cotton germplasm have been cited as an area of concern by a number of cotton researchers (Duvick 1984;Meredith 1991;Iqbal et al. 2001). Transfer of desirable genes through introgression from germplasm resources of other Gossypium species could play an important role in increasing genetic variability in Upland cotton. ...
Since Upland cotton (Gossypium hirsutum) is known to have relatively low levels of genetic diversity, a better understanding of variation and relationships among
possible sources of novel genes would be valuable. Therefore, analysis of genetic variation of the genus Gossypium, especially the diploids, which are the putative donors of the A and D genomes for the commercially important allotetraploid
cottons (AADD), G. hirsutum and G. barbadense, could provide important information about the feasibility of using these genetic resources for cotton improvement. The primary
objective of this study was to analyze the genetic diversity in A-genome diploid cotton species, G. herbaceum (A1) and G.␣arboreum (A2) by using microsatellite markers. Forty-one A-genome germplasm accessions were evaluated with 32 microsatellite loci.
Genetic similarities between A1 and A2 ranged from 0.62 to 0.86 with a mean of 0.70. Within each A-genome species similarities
ranged from 0.80 to 0.97 with a mean of 0.89 for A1 and from 0.82 to 0.98 with a mean of 0.89 for A2. A UPGMA tree and principal
coordinate analysis based on genetic similarity matrices showed distinct clusters consistent with the genomic groups.
... However, the relatively narrow gene pool [2] and the heavy use of a small number of parents by competing breeding programs have led to a low genetic diversity among Pea cultivars [3]. Extensive use of closely related cultivars by producers could result in vulnerability to pests and disease [4,5]. Determination of genetic diversity of any given crop species is a suitable precursor for improvement of the crop because it generates baseline data to guide selection of parental lines and design of a breeding scheme [6]. ...
Four RAPD primers (GM 10 , GM 37 , GM 52 and GM 100) were used to estimate genetic diversity in five Pisum cultivars. A total of 16 bands were scored corresponding to an average of 4 bands per primer with 6 bands showing polymorphism (37.5%). One out of 4 primers gave 75% polymorphism. Jaccard similarity coefficient ranged from 0.7692 to 0.9630. Similarity index reveals the maximum similarity between cultivars KPMR 925(G 2) and KPMR 926(G 3) , KPMR 926(G 3) and KPMR 927(G 4) i.e. 0.9630 and 0.963 respectively while distantly related cultivars were KPMR 922(G 1) and KPMR926(G 2) with Similarity index 0.7692. A dendrogram constructed based on the UPGMA clustering method revealed two major clusters. Cluster-I and Cluster-II comprising of two cultivars each. The cultivar KPMR 922(G 1) occupies a distinct place as revealed in the dendrogram.
... Molecular Marker based Genetic Diversity Analysis (MMGDA) also potential for assessing changes in genetic diversity over time and space [18]. Band position in comparative SSR profile for each genotype and primer combination was scored from the respective gel images. ...
Aim: The knowledge of genetic diversity and relationship among the genotypes play a significant role for genetic enhancement in breeding programmes to increase production, improve quality, biotic and abiotic stresses, and also for the selection of superior parental lines in rice. The present field experiment was conducted to study the diversity present in 29 local genotypes of rice using both morphological and molecular ways. Methodology: The experiment was conducted at Agricultural Research Farm, Banaras Hindu University, during Kharif-2017 in an augmented block design with 29 rice genotypes including 3 checks. Mahalanobis' D 2 analysis was carried out to assess the morphological diversity present among the genotypes and molecular analysis was done with 21 polymorphic SSR markers using the NTSYSpc software. Original Research Article Singh et al.; CJAST, 39(22): 92-104, 2020; Article no.CJAST.59380 93 Results: Mahalanobis' D 2 grouped the 29 genotypes into 6 clusters based on the inter-se genetic distance. The highest intra-cluster distance was recorded in the Cluster I (32.73), which comprised of 7 genotypes. The highest inter-cluster distance (65.86) was observed between Clusters IV and V. Molecular diversity analysis grouped the 29 rice genotypes into 2 main clusters i.e. cluster I and cluster II with dissimilarity coefficient of 0.34, which were further divided into sub-clusters. Polymorphic Information Content (PIC) value is an evidence of diversity and frequency among the varieties. The level of polymorphism varied from 0.164 to 0.694, with an average 0.521. The highest PIC value was observed for locus RM 5 (0.694) followed by RM 510 (0.692). All the 21 primers showed polymorphism and the number of alleles ranged from 2 to 4 with an average of 3.04. Conclusion: This study established the presence of considerable amount of genetic diversity among the genotypes studied, the most diverse genotypes being Anupam gold and HUR-1309 followed by Kalanamak-2 and HUR-1304. Breeders may attempt hybridization among the above genotypes which showed maximum diversity, for creating more variability in rice and can be used for planning further breeding programmes.
... Therefore, efforts have been established to predict hybrid performance by using morphological, agronomical traits and different molecular markers. Different methods have been used to identify genetic diversity in the maize genotypes, as morphological characterization (Goodman and Bird, 1977), pedigree analysis (Duvick, 1984), heterosis data (Smith and Smith 1989), and the detection of variation at the genomic DNA level using molecular markers. Molecular marker techniques provide effective, fast, accurate and appropriate tools for crop improvement. ...
... Farmers' varieties are important crop genetic resources and are valued by plant breeders and farmers because of diversity (heterogeneous population), rarity (embodying unique traits) and adaptability (exhibiting wide ecological and socio-cultural adaptation) (Brush and Meng, 1998;FAO, 1998;Smale, 2006). Farmers throughout the world continue to maintain and manage farmers' varieties within their production systems (Hawkes, 1971;Duvick, 1984;Brush et al., 1995;Brush, 2004;Jarvis et al., 2008;FAO, 2010). Yet the value they contain for the farming communities that maintain them has not been fully capitalized on. ...
The objective of this study was to assess the performance of farmers' and improved varieties of barley for yield and yield related traits and seed quality attribute in North Shewa Zone of Oromiya Region, Ethiopian. Seven farmer's varieties (FVs) and three improved varieties (MVs) of barley were tested at three locations in Degem Wereda in randomized complete block design (RCBD) design with three replications during 2010 Meher (June-September) cropping season. Barley seed obtained from experimental plots was used to make seed quality analysis such as physical purity, germination, vigour and health as per ISTA procedures and methods (1996). Garbuu Ggurracha was superior in yield potential and seed quality traits for meher season. Damoy is suitable variety for belg season production due to its early maturity and low moisture requirement. Statistically, grain yield was significant (p<0.01) variation was observed among varieties tested for important quantitative traits across locations indicating the presence of variability among genotypes. The analytical purity of seed samples collected from field experiment was ≥ 98.17% which was greater than the national seed standard (85%). At harvest, barley seed exhibited dormancy and germinate poorly. Significant differences in seed germination were observed between the first (after one month) and the second (after four months) test which could be attributed to thick hull character which may warrant further investigation. Sixteen different fungi genera were identified from the seed samples among which eight are known to be seed transmitted and the rest causing seed deterioration. In general significant different was observed among varieties for different pathogen infection. This study may indicate greater yield response through direct selection in barley landraces. This may be the nature of FVs' with better adaptive traits to variable environmental factors which has paramount importance for the local farmers to reduce risk. Minimum improvement for adopting early maturing varieties in an area of short rainfall to attain food security is vital. Attention should be given for conservation and improvement of farmers' varieties.
... For the assessment of gene diversity, molecular markers have generally been superior to morphological, pedigree, heterosis and biochemical data (Melchinger et al., 1991). Genetic diversity is commonly measured by the genetic distance or genetic similarity, both of which imply that there are either differences or similarities at the genetic level (Weir, 1990) and has the potential for evaluating variations in genetic diversity over time and space (Duwick, 1984). According to previous research, the Japonica population is genetically less diverse than the Indica population when studied using different genetic markers, regardless of sample size of rice accessions (Zhang et al., 1992;Ni et al., 2002). ...
Holistic and growth stage-specific screening is needed for identifying tolerant genotypes and for formulating strategies to mitigate the negative effects of abiotic stresses on crops. The objectives of this study were to characterize the genetic variability of 100 rice lines for early-season vigor, growth and physiological plasticity, and drought and temperature tolerance. Five studies were conducted to accomplish these objectives. In study 1 and 2, 100 rice genotypes consisting of several cultivars and experimental breeding lines were characterized for early-season vigor using several shoot and root morphological, physiological, and yield related traits. In study 3, low- and high-temperature tolerance assessed on select rice cultivars/hybrids during early-season. In study 4, genotypic variability in response to drought stress tolerance using morpo-physiological traits including roots was assessed under pot-culture conditions in a mini-greenhouse conditions. In study 5, the 100 rice genotypes were used to identify and validate SNP markers, and genome-wide association study (GWAS) to generate genotypic and phenotypic data with the objective of identifying new genetic loci controlling drought stress traits. Significant variability was recorded among rice genotypes and treatments for many traits measured. Early-season cumulative vigor response indices (CVRI) developed by summing individual responses indices for each trait varied among the rice genotypes, 21.36 (RU1404196) to 36.17 (N-22). Based on means and standard deviation of the CVRI, rice genotypes were classified as low- (43) and moderately low- (33), high- (16), and very high-vigor (5) groups. Total low-temperature response index values ranged from 18.48 to 23.15 whereas total high-temperature responses index values ranged from 42.01 to 48.82. Antonio, CLXL 745, and Mermentau were identified as sensitive to cold- and heat, and XL 753 was highly cold and heat tolerant genotypes tested. A cumulative drought stress response index (CDSRI) values varied between 14.7 (CHENIERE) and 27.9 (RU1402174) among the genotypes tested. This preliminary analysis of GWA indicated that substantial phenotypic and genotypic diversity exists in the 100 rice genotypes, despite their narrow genetic pool. The stress tolerant and high vigor rice genotypes will be valuable for rice breeders for developing new genotypes best suited under growing environments prone to early-season drought and temperature.
... One 386 way to minimize the effects of salt and anaerobic 387 stress on plant growth and yield is through the 388 introduction of species/varieties capable of 389 tolerating soil salinity and waterlogging. Simul-390 taneously appropriate strategies for integrated (Duvick 1984;FAO 2010). This is more perti- (Table 4). ...
In the coastal and humid tropical island region, water logging and soil salinity
are serious threat to the sustainability of rainfed agriculture due to sea water
inundation and intensive monsoon rainfall. In addition, there has been a
marked change in surface temperature, rainfall, evaporation, and extreme
events linked to climate change affecting the tropical islands. Therefore, an
innovative management of waterlogged and saline soils of island ecosystem
is imperative for sustainable agricultural production. The current technology
enables the transfer of desirable genes from wild relatives to cultivated plants
and improvement of land races followed by selection of crops and their
varieties by the island farming community for waterlogged and saline
conditions. The available evidences suggests that crop planning, multistress
crop combinations, integrated farming system, and suitable agro-forestry
models have the potential to provide the basic needs of the people even
under stressful and climate change situations. Land shaping measures have
great potential to address waterlogged and salinity together while it promotes
crop and farming system diversification which are more sustainable than
monocropping with rice. In island conditions, rain water harvesting,
storage, and its efficient use should be an integral part of the strategy for
sustainable agricultural production. In addition, the livelihood of the people
can be enhanced by suitable aquacultural practices in the coastal saline soils
while sea weed cultivation holds greater promise to diversify the agricultural
activities in the island saline environment.
... The precise evaluation of crop wild relatives is pre-requisite to identify target traits of interest followed by their introgression into the background of cultivated varieties for enhancing genetic gains [20][21][22]. A wide range of variation in wild lentil accessions was observed against the target traits viz. ...
Domesticated lentil has a relatively narrow genetic base globally and most released varieties are susceptible to severe biotic and abiotic stresses. The crop wild relatives could provide new traits of interest for tailoring novel germplasm and cultivated lentil improvement. The primary objective of this study was to evaluate wild lentil accessions for identification of economically viable agro-morphological traits and resistance against major biotic stresses. The study has revealed substantial variations in seed yield and its important component characters. Further, the diversity analysis of wild accessions showed two major clusters which were bifurcated into sub-clusters, thereby suggesting their wider genetic divergence. However, principal component analysis exhibited that seed yield plant⁻¹, number of seeds plant⁻¹, number of pods plant⁻¹, harvest index and biological yield plant⁻¹ contributed significantly to the total genetic variation assessed in wild lentil taxa. Moreover, some of the wild accessions collected from Syria and Turkey regions showed resistance against more than one disease indicating rich diversity of lentil genetic resources. The identification of most promising genotypes carrying resistance against major biotic stresses could be utilized in the cultivated or susceptible varieties of lentil for enhancing genetic gains. The study has also identified some trait specific accessions, which could also be taken into the consideration while planning distant hybridization in lentil.
... Therefore, we are bound to utilize available genetic resource and crop-wild relatives to improve these traits. No doubt, wild relatives are a rich source of new beneficial genes but linkage of unwanted traits and sterility reduces their effectiveness in boosting germplasm's genetic diversity (Duvick 1984). The genetic bridges (usage of a third parent in between two parents) can break crossing barriers in between divergent species (Hussain and Williams 1997;Reagon and Snow 2006) and choice of small DNA fragments (translocations) can be advantageous to get rid of unwanted traits. ...
Main conclusion
Tripsacum dactyloides is closely related to Zea mays since Zea perennis and the MTP tri- species hybrid have four possible reproductive modes.
Eastern gamagrass (Tripsacum dactyloides L.) and tetraploid perennial teosinte (Zea perennis) are well known to possess genes conferring resistance against biotic and abiotic stresses as well as adaptation to flood and aluminum toxic soils. However, plant breeders have been hampered to utilize these and other beneficial traits for maize improvement due to sterility in their hybrids. By crossing a tetraploid maize-inbred line × T. dactyloides, a female fertile hybrid was produced that was crossed with Z. perennis to yield a tri-genomic female fertile hybrid, which was backcrossed with diploid maize to produce BC1 and BC2. The tri-genomic hybrid provided a new way to transfer genetic material from both species into maize by utilizing conventional plant breeding methods. On the basis of cytogenetic observations using multi-color genomic in situ hybridization, the progenies were classified into four groups, in which chromosomes could be scaled both up and down with ease to produce material for varying breeding and genetic purposes via apomixis or sexual reproduction. In the present study, pathways were found to recover maize and to obtain specific translocations as well as a speedy recovery of the T. dactyloides–maize addition line in a second backcross generation. However, phenotypes of the recovered maize were in most cases far from maize as a result of genetic load from T. dactyloides and Z. perennis, and could not be directly used as a maize-inbred line but could serve as an intermediate material for maize improvement. A series of hybrids was produced (having varying chromosome number, constitution, and translocations) with agronomic traits from all three parental species. The present study provides an application of overcoming the initial interspecific barriers among these species. Moreover, T. dactyloides is closely related to Z. mays L. ssp. mays since Z. perennis and the MTP tri- species hybrid have four possible reproductive modes.
... The comparatively narrow gene pool (Hebblethwaite et al. 1985) as well as the hefty use of a petty numbers of cultivars as parents in competing breeding programs have directed to a little genetic mixture among pea cultivars (Simioniuc et al. 2002;Baranger et al. 2004), resulting in vulnerability to pests and diseases (Duvick 1984;Cox et al. 1986). This study reported that at proliferation of grain legume production by thorough utilization of high yielding cultivars enriched with tolerance to biotic and abiotic stresses. ...
p class="abstrakinggris"> Pea (Pisum sativum L .) is the second most important legume crop worldwide after chickpea ( Cicer arietinum L .) and valuable resources for their genetic improvement. This study aimed to analyze genetic diversity of pea cultivars through morphological and molecular markers. The present investigation was carried out with 12 pea cultivars using 28 simple sequence repeat markers. A total of 60 polymorphic bands with an average of 2.31 bands per primer were obtained. The polymorphic information content, diversity index and resolving power were ranged from 0.50 to 0.33, 0.61 to 0.86 and 0.44 to 1.0 with an average of 0.46, 0.73 and 0.76, respectively. The 12 pea cultivars were grouped into 3 clusters obtained from cluster analysis with a Jaccardd’s similarity coefficient range of 0.47-0.78, indicating the sufficient genetic divergence among these cultivars of pea. The principal component analysis showed that first three principal components explained 86.97% of the total variation, suggesting the contribution of quantitative traits in genetic variability. The contribution of 32.59% for number of seeds per plant, stem circumference, number of pods per plant and number of seeds per pod in the PC1 leads to the conclusion that these traits contribute more to the total variation observed in the 12 pea cultivars and would make a good parental stock material. Overall, this SSR analysis complements morphological characters of initial selection of these pea germplasms for future breeding program. </p
... Crop improvement often utilizes landrace diversity in the development of new cultivars [8,24], particularly when developing cultivars for marginal environments. Although, breeders more routinely focus their eforts on a limited gene pool of advanced cultivars or breeders' lines which are more easily utilized without successive backcrossing to eradicate the undesirable traits introduced with the desirable [67,68]. ...
... The narrow crop genetic base is forcing plant breeders to search for new adaptive traits of interest. The introduction, characterization, evaluation, identification, and utilization of unadapted gene sources for useful traits are prerequisites conducting successful base broadening programme in annual crop plants [34][35][36]. The results pertaining to chickpea interspecific hybridization accomplished under two growing seasons help us to conclude those longer days during summer season and optimum temperature has pivotal role in pod and seed setting. ...
The wild species of chickpea have tremendous potential for enhancing genetic gains of cultigen and have resistant accessions against major biotic and abiotic stresses. In the present study, two wild annual accessions, one each of C. reticulatum Ladiz. (ILWC 229) and C. echinospermum Davis (ILWC 246) were assessed for their agro-morphological features and hybridized with different cultivated varieties (BGD 72, PBG 5, ICKG 96029, Pusa 372 and JG 11) of chickpea. Fertile F1 plants were developed as revealed by their normal meiotic chromosomal configuration including high pollen stainability percentage and seed set. The effect of genetic and non-genetic factors on crossability performance with respect to pod and seed set was also evident under two growing conditions of North-Western Indian Himalayas. The segregation analysis using F2 phenotypic ratio of some distinct morphological (plant growth habit, stem pigmentation at seedling stage and testa texture) characters indicated their monogenic inheritance pattern. The study would also be useful to chickpea breeders to identify true to type interspecific plants. Further, the F1, F2 and F3 generations of all seven crosses along with parents were evaluated under natural field condition to determine the extent of variability created into the cultivated background of chickpea. There was a wide range of variation in F3 population against cold stress, suggesting selection of tolerant recombinant lines at an early stage. We also studied fruitful heterosis (%) as a useful approach, instead of residual heterosis to identify better performing transgressive segregants. The values of most of the interspecific crosses for important traits assessed in F2 and F3 generations were higher than that of better parent, suggesting isolation of inbred vigour for pod numbers and earliness. The results indicated that wild Cicer annual accessions of C. reticulatum and C. echinospermum species can be exploited after proper screening for traits of interest for diversification of cultivated gene pool and subsequent use in chickpea improvement.
... Although many more genetic and trait data are now available for PGR, detailed knowledge of highest priority for stewardship. But ongoing support for PGR maintenance in genebanks has been largely insufficient (Duvick, 1984;Geiling, 2016;Fu, 2017), exemplifying the broader paradox highlighted by the author Kurt Vonnegut, Jr.: "Another flaw in the human character is that everybody wants to build and nobody wants to do maintenance" (Vonnegut, 1990). Notwithstanding this "flaw," securing the requisite support for PGR maintenance must be achieved to safeguard our agricultural future. ...
Humanity’s survival depends on crops—the green line standing between us and calamity. To meet ever expanding human needs, crops must become increasingly more productive, mainly through genetic gains that exploit diverse plant genetic resources (PGR), the raw materials for crop breeding. For millennia, PGR have been conserved by individuals, communities, and organizations. These stewards of our agricultural future have been nearly as diverse as the PGR that they have conserved. Their invaluable roles in underpinning the security of global agriculture have largely been underappreciated. Furthermore, the challenges and complexity of successful PGR stewardship have been inadequately recognized. This paper pays tribute to these stewards’ characteristic attributes and their contributions to PGR conservation and sustainable use. It describes the pervasive impacts of PGR on crop agriculture and explains how numerous factors have affected PGR stewardship capacities. Plant genetic resource stewardship involves many different components, which are typically conducted over extended timeframes. Sustained, adequate support for PGR maintenance, a key component, has been the exception rather than the rule. Past and present PGR stewardship successes and challenges furnish numerous lessons for meeting future demands. Such lessons include recognizing the importance to PGR stewardship of: dedicated and diverse PGR stewards, continual and persistent financial support for PGR genebanks and their staffs, protecting crop wild relatives, and safeguarding genebank collections from extreme weather and introduced pests and pathogens. In the future, PGR stewardship might be conducted more frequently and more adequately by multi-institutional networks enabled by advances in information technology and artificial intelligence. © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA.
... The number of accessions available for breeding programs is lower than the total number of accessions registered in active germplasm banks (AGBs), mainly due to the technical and financial difficulties in the maintenance and characterization of AGB accessions. The lack of information related to the accessions maintained in collections and AGBs is the main challenge for their use in programs focused on genetic variability in breeding (Duvick 1984;Nass 2011). ...
The genus Passiflora, commonly known as passion fruit, is prominent in the family Passifloraceae due to its numerous species (approximately 520) and economic importance. The biodiversity of this genus is widely represented in the Americas, where Colombia and Brazil harbor approximately 170 and 150 species of Passiflora, respectively. The economic interest in passion fruit species emerged due to the beauty of their flowers, their active medicinal properties, their essential oils that can be extracted for the cosmetics industry and their production of fruit for consumption or for obtaining derivatives. Brazil is considered the largest producer of passion fruit, although its national productivity is low (an average of 14 mt/ha/year) compared with the potential for passion fruit cultivation (50 mt/ha/year). This low productivity is partly caused by a lack of cultivars adapted to different production regions and their susceptibility to major diseases. Although the number of passion fruit breeding programs has increased, the results obtained thus far have been modest compared with existing demands. Such programs therefore represent a burgeoning field of research and financial investment. Among the obstacles faced by breeders, the low representation of Passiflora in germplasm banks (considering its species richness and wide geographical distribution) and the scarcity of biological and agronomic information for most accessions are the most salient. Despite the difficulties encountered in Passiflora research over the past two decades, there has been a notable increase in the use of molecular tools for the characterization of this genus and in the number of cultivars registered and effectively available for the large-scale production of passion fruit. Thus, in this chapter, we present an overview of innovations and modern technologies, including advances in breeding programs and molecular tools, related to the availability of genetic resources for Passiflora. These technologies can be used as strategies to improve every stage of breeding programs, from pre- to post-breeding. Finally, we discuss future perspectives for studies leading to the genetic breeding of passion fruit (Passiflora spp.).
Biocultural diversity is the ever-evolving and irreplaceable sum total of all living organisms inhabiting the Earth. It plays a significant role in sustainable productivity and ecosystem services that benefit humanity and is closely allied with human cultural diversity. Despite
its essentiality, biodiversity is seriously threatened by the insatiable and inequitable human exploitation of the Earth’s resources. One of the benefits of biodiversity is its utilization in crop improvement, including cropping improvement (agronomic cultivation practices)
and genetic improvement (plant breeding). Crop improvement has tended to decrease agricultural biodiversity since the origins of agriculture, but awareness of this situation can reverse this negative trend. Cropping improvement can strive to use more diverse cultivars and a broader complement of crops on farms and in landscapes. It can also focus on underutilized crops, including legumes. Genetic improvement can access a broader range of biodiversity sources and, with the assistance of modern breeding tools like genomics, can facilitate the introduction of additional characteristics that improve yield, mitigate environmental stresses, and restore, at least partially, lost crop biodiversity. The current legal framework covering biodiversity includes national intellectual property and international treaty instruments, which have tended to limit access and innovation to biodiversity. A global system of access and benefit sharing, encompassing digital sequence information, would benefit humanity but remains an elusive goal. The
Kunming-Montréal Global Biodiversity Framework sets forth an ambitious set of targets and goals to be accomplished by 2030 and 2050, respectively, to protect and restore bicultural diversity, including agrobiodiversity.
Background: Rice (Oryza sativa L.) is grown in various parts of Zambia. Response of available varieties towards biotic (bacterial and fungal pathogens) and abiotic factors such as water stress remains unavailable. A systematic rice seed system or breeding program appears to be non-existent. This study was undertaken to assess the genetic diversity among some selected Zambian rice accessions using simple sequence repeat (SSR) molecular markers. Methods: Thirty accessions were selected for genetic diversity analysis using ten SSR markers (RM5, RM168, RM7, RM13, RM225, RM452, RM211, RM205, RM413 and RM46) selected from various chromosomal loci of the rice genome. Rice genomic DNA was amplified by the polymerase chain reaction and products were analyzed by 1% agarose gel electrophoresis. Most products appeared as single alleles in form of single bands averaging between 79-200 base pairs (bp). Significant relatedness within and among accessions was observed while most of the primers showed distinct polymorphism. Cluster analysis via a dendrogram revealed that most of the accessions were closely related and clustered into two major groups designated A and B. Result: Only one accession (ZM8321) appeared to be distinct and distantly related to all the other 29 accessions Cluster B contained the rest of the 29 accessions which were subdivided into 8 sub-clusters. Of the 29, accessions ZM8295 from Samfya District and ZM8313 from Kaputa district showed 100% similarity meaning that they are the same accession.
Plant genetic resources are the most treasures and essential basic raw materials to fulfill the current and future needs of crop improvement programmes. Plant genetic resources represent both the premise for agricultural development and a store house of genetic adaptability that acts as a buffer against environmental change. A wider genetic base, thus, assumes priority in plant breeding research aimed toward developing new varieties for increased crop production. This diversity comprises native landraces, elite cultivars, local selections, and wild relatives of crop plants. The erosion of these resources imperil world food security. The need to conserve and utilize plant genetic resources as a buffer against an unpredictable future is well recognized. The collection and conservation of this diversity in a systematic manner is the primary responsibility of all plant genetic resources institutes/centres: actually, within the national context, in all those countries which hold native genetic diversity, the scientists, planners and policy makers have a challenge on how best the prevailing genetic diversity are often preserved and utilised for the benefit of mankind. Plant genetic resources are thus our heritage which requires conservation for posterity.
Wild Chinese prickly ash resources provide a valuable genetic resource for Zanthoxylum bungeanum Maxim improvement and breeding. The Qinling Mountains was an abundant source for wild Chinese prickly ash. In this study, the phenolic and flavonoid compounds of wild germplasm resources from different altitudes and six cultivated varieties were analyzed by high performance liquid chromatography (HPLC). The chromatograms of them were essentially consistent, although their chemical composition contents were greatly different. The thirty samples were divided into three categories through the hierarchical clustering analysis. Catechin, hyperoside and quercitrin were considered to be key compounds for the quality evaluation, and by contrast, the wild samples with an altitude of 2300±50 m (Group IV) had the highest content of key compounds, and presented stronger antioxidant activity and antibacterial ability, indicating that these wild samples could be identified as the excellent breeding resources. This is the first time to evaluate the quality of wild Chinese prickly ash at different altitudes in Qinling Mountains. These excellent wild germplasm resources provided substantial potential accessions for use directly in Chinese prickly ash breeding programs.
Crop diversity underpins the productivity, resilience and adaptive capacity of agriculture. Loss of this diversity, termed crop genetic erosion, is therefore concerning. While alarms regarding evident declines in crop diversity have been raised for over a century, the magnitude, trajectory, drivers and significance of these losses remain insufficiently understood. We outline the various definitions, measurements, scales and sources of information on crop genetic erosion. We then provide a synthesis of evidence regarding changes in the diversity of traditional crop landraces on farms, modern crop cultivars in agriculture, crop wild relatives in their natural habitats and crop genetic resources held in conservation repositories. This evidence indicates that marked losses, but also maintenance and increases in diversity, have occurred in all these contexts, the extent depending on species, taxonomic and geographic scale, and region, as well as analytical approach. We discuss steps needed to further advance knowledge around the agricultural and societal significance, as well as conservation implications, of crop genetic erosion. Finally, we propose actions to mitigate, stem and reverse further losses of crop diversity.
Increase in the food demand and unprecedented level of environmental stresses have created major challenges to ensure global food security. Under such circumstances, wild species of crops serve as a genetic reservoir to improve yield, quality and adaptability of modern cultivars. Previously reported work of the introduction of genes from wild to cultivated species has drawn the attention of plant scientists towards the role of wild species in crop improvement. Contemporary genomic tools can also be exploited to understand the genetic architecture and diversity of crop wild relatives for their efficient use in practical plant breeding. Considering the value of wild genetic resources in sustainable agriculture, numerous worldwide efforts have been made for its preservation. In view of its importance, this chapter is written on a broader prospective to highlight the utilization and conservation of crop wild germplasm.
The genus Gossypium is comprised of more than 50 genetically diverse species with different origins and ploidy levels. Each of cultivated and wild species is a source of unique alleles to improve cotton crop under ever increasing fiber demand and rapidly evolving climatic factors. Formerly, most of the improvement has been made in cotton germplasm by utilizing the genetic diversity of only cultivated types of species. The plenty of examples are reported for the utilization of wild cotton species in plant breeding despite of the fact of proven to be a novel genetic resource. The major hindrance was the transfer of genetic material which is now easier as compared to past due to advancement of gene transfer methods and technologies. Therefore, the conservation and utilization of cotton wild germplasm have gained much importance and is now become imperative to sustain the yield and quality of cotton fibers. This chapter highlights the background and potential of wild species of cotton to improve yield, quality, and adaptability of modern cultivars.
Maize is one of the plant species with the greatest genetic variability. This large diversity is expressed in maize cultivated in different environments and used for many purposes, as well as in maize maintained in the germplasm banks (GB). Maize is originated from the Mesoamerican Diversity Center, which was widespread and formed thousands of races and landraces adapted to many environmental conditions. Great breeding effort has been carried out in maize, in which hybrid technology was available since 1920s in the United States of America, as a good breeding strategy. The genetic improvement carried out in the maize collections generated the elite or improved germplasm, which is genetically distant from the collections maintained in the GBs (unimproved germplasm). Thus, the elite germplasm has high yield performance, uniformity, and narrow genetic basis whereas the accessions of GBs in general have low productivity, high stalk and root lodging, high plant and ear height, large variability between individuals and broad genetic basis. Due to these differences, accessions of GBs are scarcely used in breeding programs. Pre-breeding links these both collections developing populations by the introgression of favorable alleles from unimproved germplasm into improved germplasm. These activities lead to better understand and to increase the use of GBs. In this context, this chapter will focus on: characteristics of maize genetic resources, demands of maize breeding programs, integration between genetic resources and breeding, knowledge of the variability maintained in maize GBs, and development of new elite populations and activities in maize pre-breeding.
Harmful effects of climate change, human interference, and environmental stresses have opened new challenges for food security and natural variability. Like other crops, the domestication of barley has led toward a significant reduction in genetic diversity and created hurdles to develop well-adapted cultivars. One of the best solutions toward these challenges is the exploitation of crop wild germplasm that niche in extreme geographical locations. Wild progenitors have potential to transfer adaptation loci in modern cultivars, which will make them fit for changing climate. Wild barley could be the potential source for genetic variability and increasing capability to withstand against biotic and abiotic stress factors and can be collected from its natural area of distribution, especially from the Mediterranean region. In this chapter, we have highlighted the significance of wild germplasm of barley and adaptive genes they have for various biotic and abiotic stress resistance/tolerance.
In order to study the morphological, phenological and yield characteristics of 70 Desi chickpea genotypes, a trial was conducted on 2007 in Research Farm of Agriculture Faculty of Ferdowsi University of Mashhad. In this study, 70 Desi chickpea genotypes from Ferdowsi University of Mashhad Seed Bank, were planted in plots without replication including one to Four planting rows at maximum length of 2.5 m and row space of 50 cm. Some characteristics were measured for each accession based on chickpea descriptors, including the days from emerging to flowering, flowering to pod setting, flowering to maturity, plant height, leaflet length and width, number of leaflet per leaf, leaf length, leaf area, number of node per main stem, number of primary, secondary and tertiary branches, flower length, pod length, number of pod per plant, number of seeds per pod, seed color and shape, 1000 seed weight, and seed yield. The results showed that rang of days from flowering to maturity were 32 to 44 days. Highest (47%) and lowest (20%) number of genotypes for days from flowering to maturity had ranges from 37 till 39 days and less than 37 days, respectively. The range of plant height among genotypes was 53 cm and MCC708 with 63 cm had the highest plant height. The height of the first pod from soil surface of 13% of genotypes was more than 15 cm. Seed yield in 64% of genotypes, those had the highest seed yield, was more than 400 gm-2 and MCC608 with 745 gm-2 had the most seed yield. In general, there was considerable diversity among chickpea genotypes for assessed characteristics. So it is possible to exploit this variation in breeding programs for improving yield of chickpea.
Identification of morphological, phenological and yield characteristics of genotypes is important in order to collect necessary information for available varieties and as a result selection of one or more specific traits. In this study, 73 Kabuli chickpea genotypes from Pulses Seed Bank of Research Center for Plant Sciences, Ferdowsi University of Mashhad, were planted in irrigated conditions at Research Farm of Agricultural Faculty of Ferdowsi University of Mashhad. Some characteristics were measured for each accession based on Chickpea Descriptors, including the days from emerging to flowering, flowering to podding, flowering to maturity, plant height, leaflet length and width, number of leaflet per leaf, leaf length, leaf area, number of node per main stem, number of primary, secondary and tertiary branches, flower length, pod length, number of pod per plant, number of seeds per pod, seed color and shape, 1000 seed weight, and seed yield. The results showed that there was not difference among the genotypes for the days from flowering to maturity, so that the difference between the lowest and the highest number of days from flowering to maturity was
11 days. According to period of flowering to maturity, the majority of genotypes (64.4%) were laid in group
34-37 days and the lowest number of the genotypes (15%) was put in group of lower than 34 days. Based on plant height, there was difference among the genotypes, so that the difference between the lowest height and the highest one was about 50cm and MCC706 with 67cm was the tallest genotype. Seed yield in 32.8% of genotypes was more than 400 g/m2 and MCC216 with 885 g/m2 produced the highest seed yield. Results of Cluster test showed that genotypes fallen in five distinct clusters, that clusters four and one had the highest and lowest seed yield, respectively. In general, there was considerable diversity among Kabuli chickpea genotypes regarding to assessed characteristics, so it may be possible to exploit this variation in breeding programs for improving yield of chickpea.
Aim. The aim of the work was to evaluate the possibilities of using the β-tubulin intron length (TBP, Tubulin Based Polymorphism) for genetic differentiation of ancient flax varieties (landraces), plants that was historically formed in Belarus. Methods. The β-tubulin first intron length polymorphism evaluating method (TBP) was used. Amplified fragments (β-tubulin introns) were fractionated by electrophoresis in non-denaturing polyacrylamide gel. DNA bands were detected using silver nitrate staining. Results. The size of the amplified fragments varied from 400 bp to 1900 bp. It was found that 25 of 30 studied varieties (landraces) were genetically heterogeneous. The total number of allele phenotypes was 7, and the value of PIC (Polymorphism Information Content) varied from 0.0 to 0.72. Conclusions. The data obtained make it possible to recommend landraces as a source of genes for increasing the genetic diversity of the existing flax gene pool, and the TBP method can be applied both in molecular-phylogenetic analysis and in molecular selection of flax. Keywords: Linum usitatissimum, landrace, molecular markers, DNA fingerprinting, β-tubulin genes, intron polymorphism.
Experiments were carried out to assess the increase in yield potential of winter wheat in the U.K. due to variety improvement since the early years of this century. The effects of other genetic changes were minimized by applying fungicide to control eyespot and foliar diseases, and by using nets to prevent lodging. The experiments were carried out in 1978 at Cambridge. One, on soil of high fertility in Camp Field, received 104 kg N/ha and the other, on soil of lower fertility in Paternoster Field, received 38 kg N/ha. Twelve genotypes were tested. Eight were varieties which formed a chronological series beginning with Little Joss, introduced in 1908. The remaining genotypes were recently developed selections from the Plant Breeding Institute and a line bred by the French breeders, Benoist.
The average yield of the 12 varieties and lines tested was 3·96 t/ha in Paternoster Field and 6·40 t/ha in Camp Field. In both fields the two highest yielding entries, Hobbit and the advanced breeding line 989/10, outyielded Little Joss by close to 40%. Benoist 10483 was the only entry for which the percentage yield advantage depended on high soil fertility.
The newer, high yielding, varieties were shorter and reached anthesis earlier than the older varieties. They had lower stem weights/m ² than the older varieties but similar maximum leaf area indices and leaf weights/m ² . Within each experiment the total dry-matter production of the varieties was similar, the increase in grain yield due to variety improvement being associated mainly with greater harvest index (ratio of grain yield to grain + straw yield).
It is argued that by a continuation of the trend towards reduced stem length, with no change in above-ground biomass, breeders may be able to increase harvest index, from the present value of about 50% to about 60%, achieving a genetic gain in yield of some 25%. As the limit to harvest index is approached, genetic gain in yield will depend on detecting and exploiting genetic variation in biomass production.
Early studies suggested that simple ecosystems were less stable than
complex ones, but later studies came to the opposite conclusion.
Confusion arose because of the many different meanings of `complexity'
and `stability'. Most of the possible questions about the relationship
between stability-complexity have not been asked. Those that have yield
a variety of answers.
The presence of genes for resistance to stem rust ( Puccinia graminis Pers. f. sp. tritici Eriks. & E. Henn.) in wheat ( Triticum aestivum L. em Thell.) was detected in entries of the 4th International Winter Wheat Performance Nursery by use of 18 isolates of rust previously characterized for virulence on 12 genes.
Several varieties appeared to have one or two genes in common ³ . The test isolates detected no genes for resistance in ‘Blueboy,’ ‘Starke,’ ‘Jyva,’ and Vakka.’ Based on this procedure, Sr 9b, 9e, 10,11, 13 , and Tt‐1 were not detected in any of the entries. While some varieties possessed other genes for stem rust resistance than those studied ⁴ .
A diallel of 45 single‐cross hybrids from 10 inbred lines of maize ( Zea mays L.), and a balanced set of 45 doublecross hybrids from the same inbred lines plus 10 commercial hybrids, were grown at 21 locations throughout the U.S. Corn Belt in 1965 and 1966. The purpose was to compare the stability of single‐cross and double‐cross hybrids. Two single crosses, as stable as any of the double crosses, were identified. These two single crosses outyielded the four commercial single crosses by 11%, and the three commercial double crosses by 13%. Although single crosses differed in their ability to respond to more favorable environments, the most important stability parameter appeared to be the deviation mean square. Since all types of gene action appeared to be involved in this stability, potentially useful single crosses must be evaluated over a wide range of environmental conditions to identify stable, high‐yielding single crosses for commercial release
The objective of our study was to determine the number of high‐yielding soybean [ Glycine max (L.) Merr.] cultivars that should be grown in mixtures or in pure stands to obtain high yield and stability of production across environments. Eighty entries prepared from 28 high yielding pure lines with a 10‐day range in time of maturity were evaluated during 1975 and 1976 at six locations in Iowa. Yields in the 12 environments ranged from 11.1 to 39.2 q/ha. The entries, which included 14 of the 28 pure lines and six mixtures each for 2 to 10, 12, and 14 components, represented 12 levels of heterogeneity.
There were no significant differences in yield between the mixtures and the mean of their components grown in pure stands (multiple pure stands). Regression of entry yields on an environmental index indicated that none of the pure lines, mixtures, or multiple pure stands had regression coefficients significantly different from each other or from unity. Average mean squares for deviations from regression were slightly smaller for mixtures than multiple pure stands and tended to decrease until mixtures had eight or more components. It was not possible, however, to define precisely the number of pure lines needed for stable production because mean squares for deviations from regression were more variable within than among levels of heterogeneity. Stable production depends on the particular cultivars or mixtures chosen as much as on the number involved. The choice between mixtures and multiple pure stands would depend on the yield of cultivars resistant to sporadic pest and soil problems, length of harvesting period desired, and the need to save pure seed.
Average soybean ( Glycine max (L.) Merr.) yields have increased considerably due to changes in cultivars and cultural practices. To evaluate the genetic improvement, yields, lodging, and plant height of 21 cultivars were determined in 3 years. Most of these cultivars were involved in essentially two cycles of recurrent selection. Yield increases were 26 and 16% for the first and second cycles of selection, respectively, while lodging decreased 21 and 20%. Plant height increased slightly.
Four major points emerge from this brief survey of the evidence:
1) The food crisis in 1974 seems to have been largely a result of distributional factors. The per capita availability of food grains from all sources, including imports, although below 1971 and 1972 levels, was probably above the average for 1963 to 1973. Comparison of available food supplies with estimated caloric and protein requirements of the population indicates that, on average, enough food was available to meet minimal requirements, with a small margin to spare. Supplies obtained through the government procurement and distribution program were especially short since the program depends primarily on the winter harvest, which failed badly in 1974. Thus, urban areas and some pockets of rural areas were badly hit. The poorest third of the population, who receive 20 to 30 percent less food than the national average even in normal times, were severely affected by higher prices, and there is little doubt that a sizable fraction of the population received inadequate diets.
2) The food supply for 1975 depends heavily on the winter harvest. If this is good, as it promises to be, widespread starvation, but not hunger, should be averted. Since the main shortfall was in the summer crop, the nature of the distribution problem will be different and shortages may be spread more evenly over the population. Nevertheless, the situation seems to forebode considerable hardship for the poorer segments of the population.
3) Food requirements will continue to grow over the foreseeable future as a result of rising population and incomes. India's agricultural resources are still relatively poorly exploited. In the short run, output can probably be increased substantially by increased fertilizer use on traditional as well as new varieties. In the longer run, increased production can be obtained from more intensive cropping, expansion of surface and groundwater irrigation, improved water management, and improved cultural practices brought about by more active agricultural research and appropriate land and pricing policies. These measures will need buttressing by an expanded food storage program if extreme hardships due to periodic drought are to be avoided.
4) India's farmers have shown considerable willingness to innovate under favorable conditions. The rate of adoption of HYV's in the first few years after their introduction was impressive. The same was true for tubewells and fertilizers. Nevertheless, many of the easy gains may already have been made. Fragmentary information on the quality of irrigation indicates that the acreage sown to wheat and rice HYV's may be approaching an upper limit in many areas because of the requirements of these varieties for a high degree of water control. Further gains will require more aggressive and coordinated policies for agricultural development. A major change in development strategy may be required if scarcities and hardships such as those currently being experienced are to be avoided in the future, and some hard political decisions on land reform and consolidation may have to be made.
It is to be hoped that bold and imaginative agricultural policies will be followed, and that they will be accompanied by greater efforts to reduce population growth to manageable levels.
Soybeans: regional distribution of major varieties
- Reporting Crop
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Cotton varieties planted, 1980 crop
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Postulation of genes for stem rust resistance in the International Wheat Per-formance Nursery I through XI Stem rust resistance of the cultivar "Waldron
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Distribution of the varieties and classes of wheat in the United States in 1979 Soybeans: regional distri-bution of major varieties Polymorphism and balancing natural selection
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India in 1974 to calculate the food potential of Iowa's maize and soybean production Bedford, a new soybean resistant to cyst nematodes. Information Sheet 1280 Sorghum germplasm base in the United States
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Using host resistance to manage pathogen populations Genetic rates of gain in hybrid maize during the past 40 years Genetic contributions to yield gains of U.S. hybrid maize
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Distribution of the varieties and classes of wheat in the United States in 1979
- L W Briggle
- S L Strauss
- D E Hamilton
- G H Howse
Bedford, a new soybean resistant to cyst nematodes. Information Sheet 1280
- E E Hartwig
- J M Epps
- E. E. Hartwig
Dawson alfalfa-a new variety resistant to aphids and bacterial wilt
- W R Kehr
- G R Mauglitz
- R L Ogden
Evaluations for resistance to corn stunt and maize dwarf mosaic diseases in corn
- C W Kuhn
- M D Jellum
Objectives and approaches to grain and forage sorghum improvement in the Americas
- A B Maunder
Polymorphism and balancing natural selection, p. 107-117. Postzygotic isolating mechanisms in animals and plants
- T Dobzhansky
- F J Ayala
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Butte, an early high yielding, hard red spring wheat
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- R H Busch
- J D Miller
- R. C Frohberg
The barberry and the wheat
- E C Large
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Stem rust resistance of the cultivar “Waldron
- A P Roelfs
Sorghum downy mildew, a disease of maize and sorghum
- R A Fredericksen
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- F R Miller
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- H J Walker
- R. A. Fredericksen
Sorghum germplasm base in the United States
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The economic impact of public investment in wheat research in the Western Region
- R J R Sims
- A A Araji
Iowa prairie-an endangered ecosystem
- D D Smith
- D. D Smith
Soybeans: regional distribution of major varieties
- Crop Reporting Board, Economics and Statistics Service, USDA
Using host resistance to manage pathogen populations
- D N Duvick
- D. N. Duvick
Postzygotic isolating mechanisms in animals and plants
- T Dobzhansky
- F J Ayala
- G L Stebbins
- J W Valentine
- T. Dobzhansky
Postulation of genes for stem rust resistance in the International Wheat Performance Nursery I through XI
- D V Mcvey
- D. V McVey