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Conservation and Use of Temperate Fruit and Nut Genetic Resources
... are being maintained in the filed gene banks of ICAR NBPGR Regional Station Shimla and Bhowali. In addition, 62 exotic accessions of blackberry and 21 accessions of blueberry procured from National Clonal Germplasm Repository, Corvallis, USA are being maintained in vitro at National Genebank, ICAR-NBPGR, New Delhi (Dar et al., 2018;Dhillon and Rana, 2003;Hassan et al., 2018;Madhu et al., 2023). ...
The horticultural sector in India has emerged as a formidable force in global production, with the nation claiming the position of the second-largest producer worldwide. In the fiscal year 2022-23, India's horticultural output reached an estimated 351.92 million tons, showcasing a notable increase of approximately 4.74 million tons (1.37%) compared to the preceding year. Fruit crops, a significant component of this sector globally, span an extensive area of approximately 68.05 million hectares, yielding a staggering 867.77 million metric tons annually, averaging 12.75 tons per hectare. India's contribution to this domain is notable, with fruit production totaling around 107.51 million metric tons, cultivated across 7.06 million hectares, boasting an average productivity of 15.22 tons per hectare. The Indian Himalayan region stands out as a promising landscape for the cultivation of temperate horticultural crops, including fruits, vegetables, ornamental plants, and medicinal and aromatic species. Encompassing latitudes 26°20' to 35°40' N and longitudes 74°50' to 95°40' E, this region spans from the foothills in the south (Siwalik's) to the Tibetan plateau in the north (trans-Himalaya), comprising approximately 95 districts of the country. Despite its fragile terrain, characterized by snow-clad peaks and dense forests, the Indian Himalayas contribute significantly, covering 16.2% of India's total geographical area. Temperate fruit cultivation thrives predominantly in Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Sikkim, and Arunachal Pradesh, capitalizing on the region's climatic advantages. Notably, a diverse range of temperate fruits such as apple, pear, peach, plum, apricot, cherry, almond, and walnut flourish in this region. With its relative climatic advantages and conducive environmental conditions, the Indian Himalayan region continues to serve as a vital hub for the production of temperate fruits, underscoring its significance in India's horticultural landscape.
The aim of this study was to achieve the cryopreservation of almond winter dormant buds using a two-step freezing method and to investigate the freezing behaviors of almond cultivars. A two-step freezing cryo-method was used after desiccation to 18–28% moisture content, and recovery conditions such as dark incubation and rehydration in sterile moist moss grass for various durations were also used for enhancing survival. Cultivars such as ‘Almond-IXL,’ ‘Merced,’ ‘Pranyaj,’ ‘Primoriskij,’ and ‘Waris’ underwent initial recovery after cryopreservation. The highest recovery was observed in the ‘Merced’ cultivar, followed by ‘Pranyaj.’ The freezing impact in different cultivars of almond dormant buds was also investigated using scanning electron microscopy (SEM) and light microscopy. All living cells in bud tissues exhibited distinct shrinkage without intracellular ice formation as a result of slow cooling (5 °C/day) of dormant buds to −30 °C, detectable by SEM. However, the re-crystallization experiment of these slowly cooled tissue cells, which was carried out by further freezing of slowly cooled buds with liquid nitrogen (LN) and then rewarming to −10 °C, confirmed that some of the cells in the apical meristem lost freezable water with slow cooling to −30 °C, indicating adaptation of these cells by deep supercooling. Deep supercooling could not occur in dormant bud primordia if xylem vessels formed a continuous conduit connecting the dormant bud primordia with the remainder of the plant. If xylem continuity was established, ice could propagate via the vascular system and nucleate the water within the primordia. It is concluded that no extracellular ice crystals accumulated in such tissues containing deep supercooling cells with thin cell walls. Some cultivars in which ice crystallization was observed could not be successfully cryopreserved.
Plums are a large group of closely related stone fruit species and hybrids of worldwide economic importance and diffusion. This review deals with the main aspects concerning plum agrobiodiversity and its relationship with current and potential contributions offered by breeding in enhancing plum varieties. The most recent breeding achievements are revised according to updated information proceeding from relevant scientific reports and official inventories of plum genetic resources. A special emphasis has been given to the potential sources of genetic traits of interest for breeding programs as well as to the need for efficient and coordinated efforts aimed at efficaciously preserving the rich and underexploited extant plum agrobiodiversity. The specific objective of this review was to: (i) analyze and possibly evaluate the degree of biodiversity existing in the cultivated plum germplasm, (ii) examine the set of traits of prominent agronomic and pomological interest currently targeted by the breeders, and (iii) determine how and to what extent this germplasm was appropriately exploited in breeding programs or could represent concrete prospects for the future.
Flower bud dormancy in temperate fruit tree species, like almond [Prunus dulcis (Mill.) D.A. Webb], is a survival mechanism that ensures flowering will occur under suitable weather conditions for successful flower development, pollination and fruit set. Dormancy is divided into three sequential phases: paradormancy, endodormancy and ecodormancy. During the winter, buds need cultivar-specific chilling requirements to overcome endodormancy and heat requirements to activate the machinery to flower in the ecodormancy phase. One of the main factors that enables the transition from endodormancy to ecodormancy is transcriptome reprogramming. In this work, we therefore monitored three almond cultivars with different chilling requirements and flowering times by RNA sequencing during the endodormancy release of flower buds and validated the data by qRT-PCR in two consecutive seasons. We were thus able to identify early and late flowering time candidate genes in endodormant and ecodormant almond flower buds associated with metabolic switches, transmembrane transport, cell wall remodeling, phytohormone signaling and pollen development. These candidate genes were indeed involved in the overcoming of the endodormancy in almond. This information may be used for the development of dormancy molecular markers, increasing the efficiency of temperate fruit tree breeding programs in a climate-change context.
Acidity is a critical component determining apple fruit quality. Previous studies reported two major acidity quantitative trait loci (QTLs) on linkage groups (LGs) 16 (Ma) and 8 (Ma3), respectively, and their homozygous genotypes mama and ma3ma3 usually confer low titratable acidity (TA) (<3.0 mg ml −1) to apple fruit. However, apples of genotypes Ma-(MaMa and Mama) or Ma3-(Ma3Ma3 and Ma3ma3) frequently show an acidity range spanning both regular (TA 3.0-10.0 mg ml −1) and high (TA > 10 mg ml −1) acidity levels. To date, the genetic control for high-acidity apples remains essentially unknown. In order to map QTLs associated with high acidity, two genomic DNA pools, one for high acidity and the other for regular acidity, were created in an interspecific F 1 population Royal Gala (Malus domestica) × PI 613988 (M. sieversii) of 191 fruit-bearing progenies. By Illumina paired-end sequencing of the high and regular acidity pools, 1,261,640 single-nucleotide variants (SNVs) commonly present in both pools were detected. Using allele frequency directional difference and density (AFDDD) mapping approach, one region on chromosome 4 and another on chromosome 6 were identified to be putatively associated with high acidity, and were named Ma6 and Ma4, respectively. Trait association analysis of DNA markers independently developed from the Ma6 and Ma4 regions confirmed the mapping of Ma6 and Ma4. In the background of MaMa, 20.6% of acidity variation could be explained by Ma6, 28.5% by Ma4, and 50.7% by the combination of both. The effects of Ma6 and Ma4 in the background of Mama were also significant, but lower. These findings provide important genetic insight into high acidity in apple.
Breeding studies in walnut (Juglans regia L.) are usually time consuming due to the long juvenile period and therefore, this study aimed to determine markers associated with time of leaf budburst and flowering-related traits by performing a genome-wide association study (GWAS). We investigated genotypic variation and its association with time of leaf budburst and flowering-related traits in 188 walnut accessions. Phenotypic data was obtained from 13 different traits during 3 consecutive years. We used DArT-seq for genotyping with a total of 33,519 (14,761 SNP and 18,758 DArT) markers for genome-wide associations to identify marker underlying these traits. Significant correlations were determined among the 13 different traits. Linkage disequilibrium decayed very quickly in walnut in comparison with other plants. Sixteen quantitative trait loci (QTL) with major effects (R2 between 0.08 and 0.23) were found to be associated with a minimum of two phenotypic traits each. Of these QTL, QTL05 had the maximum number of associated traits (seven). Our study is GWAS for time of leaf budburst and flowering-related traits in Juglans regia L. and has a strong potential to efficiently implement the identified QTL in walnut breeding programs.
Worldwide, plum is one of the main species, occupying an area of about 2,600,000 ha and ensuring production about 11,700,000 tons. Even though there are over 6000 plum cultivars belonging to 19-40 species, there is still the need to create new cultivars due to the demands of growers and consumers. In addition, the large plum-growing countries (Romania, Serbia, Germany, Bulgaria, etc.) have decreased production due to plum pox virus (PPV) attack. Therefore, these countries developed breeding programs with the following objectives: resistance/ tolerance to PPV, productivity, fruit quality, late blooming, self-fertility, different ripening times, short growing period, spur fructification, etc. Using different breeding methods (controlled hybridization, open pollination, selection in wild population on Prunus sp., and mutagenesis), in the last years, over 450 plum cultivars were released, from which 70% represent European cultivars and 30% Japanese cultivars.
Background:
Unravelling the genetic architecture of agronomic traits in walnut such as budbreak date and bearing habit, is crucial for climate change adaptation and yield improvement. A Genome-Wide Association Study (GWAS) using multi-locus models was conducted in a panel of 170 walnut accessions genotyped using the Axiom™ J. regia 700 K SNP array, with phenological data from 2018, 2019 and legacy data. These accessions come from the INRAE walnut germplasm collection which is the result of important prospecting work performed in many countries around the world. In parallel, an F1 progeny of 78 individuals segregating for phenology-related traits, was genotyped with the same array and phenotyped for the same traits, to construct linkage maps and perform Quantitative Trait Loci (QTLs) detection.
Results:
Using GWAS, we found strong associations of SNPs located at the beginning of chromosome 1 with both budbreak and female flowering dates. These findings were supported by QTLs detected in the same genomic region. Highly significant associated SNPs were also detected using GWAS for heterodichogamy and lateral bearing habit, both on chromosome 11. We developed a Kompetitive Allele Specific PCR (KASP) marker for budbreak date in walnut, and validated it using plant material from the Walnut Improvement Program of the University of California, Davis, demonstrating its effectiveness for marker-assisted selection in Persian walnut. We found several candidate genes involved in flowering events in walnut, including a gene related to heterodichogamy encoding a sugar catabolism enzyme and a cell division related gene linked to female flowering date.
Conclusions:
This study enhances knowledge of the genetic architecture of important agronomic traits related to male and female flowering processes and lateral bearing in walnut. The new marker available for budbreak date, one of the most important traits for good fruiting, will facilitate the selection and development of new walnut cultivars suitable for specific climates.
Woody perennial plants make up nearly half of plant diversity and represent one‐third of the world's major crop species, yet effective strategies to maintain and preserve these important species require additional attention. The majority of conservation programs focus on seed storage; however, seeds of many woody perennial plants are difficult to maintain in seed banks because they are recalcitrant. In addition, most woody perennial crops are clonally propagated, and seed‐based conservation efforts miss clonal lineages that form the foundation of woody perennial agriculture. Woody crops are often best maintained as living collections, but these compose only 5.8% of ex situ germplasm collections. Living germplasm collections are critical resources for exploring and conserving genetic and phenotypic diversity and provide novel material for breeding efforts. In this review, we examine how living germplasm collections can be used for for phenotypic description, genetic characterization, and plant breeding. Lastly, we outline the importance of conserving these valuable resources and highlight the need for conservation strategies that are appropriately designed for woody perennial species.
Globally India is the second largest producer of fruits; however the productivity is significantly low as compared to advanced countries. The majority of the temperate fruits and nuts are being cultivated in the north-western Himalayan and small areas are lies in north eastern parts. High altitude and temperate regions are capable to produce good quality fruits. But the foothill where the chilling is insufficient adversely affects the yield and quality. In India, majority of the temperate fruits were introduced from other parts of the world and some are indigenous to India like walnuts and wild apple species. Therefore, the improvement of the temperate fruits and nuts were taken place mainly through introduction of promising cultivars. The exotic cultivars are still the backbone of fruit production in India particularly for apple, pear, peach, plum and cherry. Promising varieties were introduced from USA, UK, Germany, Italy, France, Australia, New Zealand, Hungary and Bulgaria and were evaluated for commercial exploitation. However, in walnutand almonds, production is mainly from Indigenous cultivars/ local land races. These consisted of non-descriptive trees and highly variable in yield and quality traits. Recently, several varieties have been developed in India in apple, peach, plum, apricot, cherry and walnut. The potential of these varieties are immense for commercial exploitation. The paper attempt to document the accomplishment made in temperate fruit and nut improvement in perspective to Indian Scenario. The information is valuable for breeders and academician for further studies.
The cryopreservation eff ect on viability of black currant cuttings (Ribes nigrum L.), sweet cherry pollen (Cerasus avium L. Moench), Prunus rossica Erem. diploid plum and Prunus domestica L. garden plum pollen, as well as the seeds of wild medicinal plants: Syrian rue (Peganum harmala L.), tansy (Tanacetum ulutavicum Tzvel.) and sawwort (Serratula dissecta Ledeb.) was studied. The viability in 5 cultivars of R. nigrum L. was decreased after cryopreservation; in 7 cultivars of C. avium L. (17 cultivars totally) it was increased, in 6 cultivars there were no changes, in 4 ones it was decreased; in 3 varieties of P. rossica Erem. (9 cultivars totally) the one was increased, in 3 ones there were no changes, in 3 ones it decreased; in 6 cul-tivars of P. domestica L. (13 cultivars totally) this index was increased, in 3 ones there were no changes, in 4 ones it decreased; in P. harmala L. seeds it was unchanged; in the seeds of S. dissecta Ledeb. it was increased. For the seeds of three medicinal plants there were selected the optimal concentrations of cryoprotectants and thawing modes as follows: P. harmama L. – 100% glycerol, slow freeze-thawing; T. ulutavicum Tzvel. – 10% sucrose, slow warming; S. dissecta Ledeb. – 3% DMSO, rapid warming.Probl Cryobiol Cryomed 2019; 29(1): 044–057Â
Walnut(Juglans regia L.) is a major nut crop of temperate region and the existing germplasm available in the country is of seedling origin, thus, contributing towards the large variability in this crop. Therefore, a research study was carried out ICAR-CITH, Srinagar to characterized and decipher the genetic variability among 27 genotypes of Indian walnut(Juglans regia L.) based on morphological characters, viz., growth habit, bearing habit, foliage, fruit and kernel characteristics for further improvement, conservation and utilization. The Erect growth habit was noticed in genotype, viz., CITH-W-12, while semi erect growth habit was noticed in majority of the genotypes. Three types of leaf shapes were recorded i,e narrow elliptic, elliptic, and broad elliptic and based on leaf characteristics all the genotypes could also be categorized viz. pubescence as glabrous, slightly pubescent and pubescent. The genotype was categorized into early, mid and late group based on their fruit maturity duration. High variability was also recorded for fruit shape viz, round, cordate, ovate, long trapezoid, and elliptic. The current findings clearly characterized each genotype and can be identified or grouped individually based on this descriptor. Present study provides the detailed morphological descriptor of walnut which can be utilised for DUS testing of walnut, varietal identification, characterization, registration, documentation etc. The database generated may be useful for comparison against the candidate varieties developed in future.
Background: Pear (Pyrus) is a globally grown fruit, with thousands of cultivars in five domesticated species and
dozens of wild species. However, little is known about the evolutionary history of these pear species and what
has contributed to the distinct phenotypic traits between Asian pears and European pears.
Results: We report the genome resequencing of 113 pear accessions from worldwide collections, representing
both cultivated and wild pear species. Based on 18,302,883 identified SNPs, we conduct phylogenetics, population
structure, gene flow, and selective sweep analyses. Furthermore, we propose a model for the divergence,
dissemination, and independent domestication of Asian and European pears in which pear, after originating in
southwest China and then being disseminated throughout central Asia, has eventually spread to western Asia,
and then on to Europe. We find evidence for rapid evolution and balancing selection for S-RNase genes that
have contributed to the maintenance of self-incompatibility, thus promoting outcrossing and accounting for pear
genome diversity across the Eurasian continent. In addition, separate selective sweep signatures between Asian
pears and European pears, combined with co-localized QTLs and differentially expressed genes, underline distinct
phenotypic fruit traits, including flesh texture, sugar, acidity, aroma, and stone cells.
Conclusions: This study provides further clarification of the evolutionary history of pear along with independent
domestication of Asian and European pears. Furthermore, it provides substantive and valuable genomic resources
that will significantly advance pear improvement and molecular breeding efforts.
Keywords: Pear (Pyrus), Re-sequencing genomes, Origin and evolution, Independent domestication, Fruit-related
traits, Self-incompatibility
Identification of the varieties is the primary requirement for characterization of the gene pool in agricultural production and implementation of breeding programs. In the present work, a set of six SSR markers was used for identification of cultural material collected on various horticultural farms in Kazakhstan: 30 varieties of Kazakhstani selection, 40 foreign varieties, and 16 Dzhangaliev’s apple clones selected in wild apple populations. Values of expected (He) and observed (Ho) heterozygosity in groups of all analyzed varieties were high: from 0.735 to 0.812 and from 0.661 to 0.721 respectively. Cluster analysis and analysis of genetic distances (STRUCTURE, UPGMA) showed a distribution of all samples into four major groups with a set of small subgroups caused by origin diversity. The first group included Kazakhstani varieties originating from Reneitte Burchardt, the second group included varieties with Aporta in parentage, the third group was represented by subclusters with a majority of foreign varieties, and the last group was composed of Dzhangaliev’s apple clones and Kazakhstani varieties with wild apple as their ancestor. Genotyping revealed inconsistencies in individual samples (and/or parentage) with claimed names. Analysis by markers of the Md-ACS1 and Md-ACO1 genes responsible for ethylene levels in fruits, which according to the literature correlates with fruit hardness and storability, did not reveal among Kazakhstani varieties any ACS1-2/2 homozygotes, the genotype with the highest expression of these traits. A quarter of Kazakhstani varieties and about a half of foreign varieties were heterozygous in ACS1, an indication of medium hardness and relatively long period of fruit storage. In two Kazakhstani and two foreign varieties heterozygous in ACS1, an improvement of the traits is possible owing to homozygosity in ACO1-1/1.
Plant breeders require genetic diversity to develop cultivars that are productive, nutritious, tolerant of biotic and abiotic stresses, and make efficient use of water and fertilizer. The USDA‐ARS National Plant Germplasm System (NPGS) is a major source for global plant genetic resources (PGR), with accessions representing improved cultivars, breeding lines, landraces, and crop wild relatives (CWR), coupled with passport and trait evaluation data. The goal of this article is to facilitate use of PGR in plant breeding programs. Our specific objectives are (i) to summarize the structure and operation of the NPGS and its consultative and support committees, (ii) to review current use of the system by plant breeders, (iii) to describe constraints to improving the utility of PGR, and (iv) to discuss ways in which the NPGS might evolve to better meet the challenges facing agriculture and society in coming decades. The NPGS will enhance its relevance to plant breeding provided there is (i) ongoing attention to filling the gaps in NPGS collections, especially for CWR; (ii) a major increase in efforts to phenotype and genotype accessions using standardized methods; (iii) enhanced information content of the Genetic Resources Information Network (GRIN)‐Global system and improved interoperability with other databases; (iv) increased attention to prebreeding activities; (v) improved training opportunities in practices for incorporating PGR in breeding programs; and (vi) expanded outreach efforts to strengthen public support for the NPGS. We believe these steps will be implemented most effectively through coordinated efforts among USDA‐ARS, universities, the private sector, and international partners.
Pear is one of the most important temperate fruits, with high genetic diversity, but controversial classification for some genotypes or species. Our study evaluates the polymorphism of 385 pear resources belonging to five cultivated species or interspecies of Pyrus, based on a set of 134 core simple sequence repeat (SSR) markers. A total of 690 variant alleles were detected, from 2 to 12 per locus, with an average of 5.45, as well as 30 rare alleles. The clustering relationship divided the pear genotypes into three groups, with the primary division between occidental and oriental pears, revealing separate evolution processes, followed by division of Pyrus ussuriensis, Pyrus pyrifolia, and Pyrus bretschneideri. Population structure analysis with K values of 2 to 8 reflected a clear genetic composition within different genotypes, supporting Pyrus sinkiangensis as a hybrid of oriental and occidental pears and P. pyrifolia and P. bretschneideri sharing a common ancestor. However, the division of genetic components also revealed separate evolution at the different geographic and environmental conditions of South China and North China. The varieties “Pingguoli” and “Chaoxianyangli,” which currently have controversial classification, were classified into P. bretschneideri and Pyrus communis, respectively. A core collection of 88 accessions was chosen, covering all of the rare alleles and 95.54 % of all alleles. The high-quality and comprehensive evaluation of a wide range of pear cultivars by core SSR markers covering the whole genome demonstrated their excellent application for the study of genetic diversity, genetic relationships, and building a core collection for pear.
Hypersensitivity resistance to the sharka virus is one of the most promising resistance mechanisms used in breeding for European plum cultivars. Its genetic determination is poorly understood as the hexaploid genome of P. domestica hampers the investigation of the inheritance of the resistance trait. A monogenic dominant inheritance can be excluded. Hypersensitive genotypes of P. domestica were crossed with genotypes of diploid myrobalan (P. cerasifera) and tetraploid sloe (P. spinosa). The descendants were tested for hypersensitivity against PPV. In order to investigate their parentage, their chromosome number was determined using a new staining technique for chromosomes in Prunus root tips. In both crossing combinations, the interspecific hybrid nature of the seedlings could be shown. Some of them showed strong hypersensitive response when inoculated with PPV. The hypersensitive interspecific hybrids are used for further crossings in order to investigate the inheritance of the trait of interest. Moreover, they are tested for their potential use as rootstocks for different Prunus species.
The fruit of apricot (Prunus armeniaca L., Rosaceae) has been used as food in FYR Macedonia since a long time ago. The chemical organic matters from the fruit is a kind material for food processing and has potential nutritional, medical and commercial values. The results based on fruit physical and chemical analyses clearly showed that different apricot genotypes have very important contents of soluble solids, individual sugars, and titratable acidity in limited soil and climatic conditions. In addition, the contents of these chemical compounds in some genotypes were higher than those in the control cultivar Hungarian Best. Using the PC analysis (PC1 = 32.13%, PC2 = 22.86%, and PC3 = 18.32%), apricot genotypes were separated into groups with similar physical and chemical attributes. These relationships may help to select a set of genotypes with better fruit quality performances which, in our study, might be indicated in DL-1/1/04, DL-1/2/03, D-1/04 and K-5/04.
Winter chill is essential for most of the plants that fall dormant in the winter in order to avoid frost damage and do not resume growth until a certain amount of winter chill has accumulated for fulfilling their chilling requirement. Climate change is likely to affect chilling requirement of temperate fruit crops significantly and therefore, the opportunity to meet this requirement will be reduced as the climate becomes warmer. Increase in average global temperature would move the existing plant species and varieties to new latitudinal belts with favourable climates. It is, therefore, possible that crops that are used to be productive in one area may no longer be so or the other way round. The resultant of these climate changes are clearly apparent in the shifting of apple cultivation from lower elevations to higher altitudes in India. Insufficient chilling greatly influences flower initiation and fruit colouration along with deterioration in fruit texture and taste. Further, the lack of proper chilling is also posing serious problems like scab disease, premature leaf fall and infestation of red spider mite in apple. High temperature and moisture stress is increasing sunburn and cracking in apple, apricots and cherries in the higher altitudes. Insufficient chilling reduces pollination, fruit set and ultimately the yield in walnuts, pistachio and peaches. Advanced flowering has been found in olive, apple and pear. Reduced flower size and pedicel lengths were observed in cherry due to less chilling. The studies regarding impact of climate change on fruit crops is meagre primarily due to lack of data, appropriate modeling and government policies. Development of low chill cultivars with greater tolerance to stresses, use of GIS to match varieties with the projected suitable production locations, development of suitable dormancy and chilling models, altering orchard microclimate and use of rest breaking chemicals are the viable approaches that can be adopted to yield reliable results on regional scale.
Mardía' is a new almond cultivar released because of its good agronomical traits and very late blooming time, 2 weeks later than 'Felisia', the latest blooming cultivar released so far. It is characterized by its slightly upright growth habit, early ripening, high and regular bloom density, autogamy (S 6 S f genotype), high fruit set, tolerance to diseases, hard shell, large kernel, very high content of oleic acid, and low content of linoleic acid.
The use of crop wild relatives (CWRs) in breeding is likely to continue to intensify as utilization techniques improve and crop adaptation to climate change becomes more pressing. Significant gaps remain in the conservation of these genetic resources. As a first step toward a national strategy for the conservation of CWRs, we present an inventory of taxa occurring in the United States, with suggested prioritization of species based on potential value in crop improvement. We listed 4600 taxa from 985 genera and 194 plant families, including CWRs of potential value via breeding as well as wild species of direct use for food, forage, medicine, herb, ornamental, and/or environmental restoration purposes. United States CWRs are related to a broad range of important food, forage and feed, medicinal, ornamental, and industrial crops. Some potentially valuable species are threatened in the wild, including relatives of sunflower (Helianthus annuus L.), walnut (Juglans regia L.), pepo squash (Cucurbita pepo L.), wild rice (Zizania L.), raspberry (Rubus idaeus L.), and plum (Prunus salicina Lindl.), and few accessions of such taxa are currently conserved ex situ. We prioritize 821 taxa from 69 genera primarily related to major food crops, particularly the approximately 285 native taxa from 30 genera that are most closely related to such crops. Both the urgent collection for ex situ conservation and the management of such taxa in protected areas are warranted, necessitating partnerships between concerned organizations, aligned with regional and global initiatives to conserve and provide access to CWR diversity.
Temperate fruit and nut species require exposure to chilling conditions in winter to break dormancy and produce high yields. Adequate winter chill is an important site characteristic for commercial orchard operations, and quantifying chill is crucial for orchard management. Climate change may impact winter chill. With a view to adapting orchards to climate change, this review assesses the state of knowledge in modelling winter chill and the performance of various modelling approaches. It then goes on to present assessments of past and projected future changes in winter chill for fruit growing regions and discusses potential adaptation strategies. Some of the most common approaches to modelling chill, in particular the Chilling Hours approach, are very sensitive to temperature increases, and have also been found to perform poorly, especially in warm growing regions. The Dynamic Model offers a more complex but also more accurate alternative, and use of this model is recommended. Chill changes projected with the Dynamic Model are typically much less severe than those estimated with other models. Nevertheless, projections of future chill consistently indicate substantial losses for the warmest growing regions, while temperate regions will experience relatively little change, and cold regions may even see chill increases. Growers can adapt to lower chill by introducing low-chill cultivars, by influencing orchard microclimates and by applying rest-breaking chemicals. Given substantial knowledge gaps in tree dormancy, accurate models are still a long way off. Since timely adaptation is essential for growers of long-lived high-value perennials, alternative ways of adaptation planning are needed. Climate analogues, which are present-day manifestations of future projected climates, can be used for identifying and testing future-adapted species and cultivars. Horticultural researchers and practitioners should work towards the development and widespread adoption of better chill accumulation and dormancy models, for facilitating quantitatively appropriate adaptation planning.
Twenty four apricot genotypes with different geographic origins, maintained in the germplasm collections of Central Institute of Temperate Horticulture, Srinagar, India, were studied by means of RAPD markers. The aim of the study was to determine the genetic relationship amongst genetypes from different eco-geographical regions. Fourty three decamer primers were used in the study. All of them were polymorphic in the set of cultivars studied and allowed every genotype to be unambiguously distinguished. A dendrogram based on UPGMA analysis grouped the 24 genotypes into four main clusters with Jaccard's similarity coefficient ranging from 0.14 to 0.86 with an average of 0.40. RAPD markers have proved to be an efficient tool for fingerprinting of cultivars and conducting genetic-diversity studies in apricot.
The genus Castanea, chestnuts and chinkapins, belongs to the family Fagaceae, which inckudes other important timber producting genera such as Quercus and Fagus. The geus Castanea is divided into three geographically delimited sections with at least seven consistently recognized interfertile species: 4 species in Asia (C. mollissima, C. henryi, C. seguinii, and C. crenata), two or more species in North America (C.dentata, C. ozarkensis, and C. pumila) and one in Europe and Turkey (C.sativa). The most important diseases of chestnut are ink disease (Phytophthora) and chesnut blight (Cryphonectria). Resistance to these is the major objetive fpr rootstock breeding in Europe and scion breeding in North America. In both cases, the source of resistance was Asian species. European breeding programs developed resistant haybrid rootstocks, which are propagated by stooling, cuttings or in vitro culture. A major pest od chestnut is the wasp Dryocosmus kuriphilus whose control is bsed on the spread of parasitoids but also on the selection of resitant cultivars. For nut production, the most importan breeding objetivs include the following: good horticultural traits, product quality, suitability to storage and processing, and ease of peeling. For timber, important characters include wood quality, rapid growth, and nonchecking of wood (ring-shake). Molecular maps have been developed, which has expanded the genetic knowledge of the chestnut. An efficient genetic transformation protocol for C. sativa through the coculture of somatic embryos with different strains of Agrobacterium has been described.
Amplified fragment length polymorphism (AFLP) analysis is a rapid and efficient method for producing DNA fingerprints and
molecular characterization. Our objectives were to: estimate genetic similarities (GS), marker indices, and polymorphic information
contents (PICs) for AFLP markers in almond cultivars; assess the genetic diversity of almond cultivars and wild species, using
GS estimated from AFLP fingerprints and molecular characterization; and facilitate the use of markers in inter-specific introgression
and cultivar improvement. The genetic diversity of 45 almond cultivars from Iran, Europe, and America, were studied assaying
19 primer combinations. In addition, several agronomic traits were evaluated, including flowering and maturity times, self-incompatibility,
and kernel and fruit properties. Out of the 813 polymerase chain reaction fragments that were scored, 781 (96.23%) were polymorphic.
GS ranged from 0.5 to 0.96, marker indices ranged from 51.37 to 78.79, and PICs ranged from 0.56 to 0.86. Results allowed
the unique molecular identification of all assayed genotypes. However, the correlation between genetic similarity clustering
as based on AFLP and clustering for agronomic traits was low. Cluster analysis based on AFLP data clearly differentiated the
genotypes and wild species according to their origin and pedigree, whereas, cluster analysis based on agronomic data differentiated
according the pomological characterization. Our results showed the great genetic diversity of the almond cultivars and their
interest for almond breeding.
Covers the genetic resources of major horticultural crops. For researchers the donor species /germplasm for different traits will be available
Freeze resistance is critical to successful dormant bud (DB) cryopreservation, and is affected by genotype, environmental conditions, dormancy phase and processing techniques. Pretreatment induced freeze resistance may contribute to more successful and efficient protocols for cryopreserving DB. Differential thermal analysis (DTA) was used to quantify the effects of cryopreservation pretreatments on freeze resistance of dormant budwood. Low temperature exotherm profiles created by DTA could rapidly identify pretreatments that are contributing to increased freeze resistance in tree fruit species. In this study, DTA was used to help elucidate the effects of varying pretreatments (sucrose, desiccation and their combination) on peach, a model crop in tree fruit physiology that has shown little cryosurvival using the dormant bud method in the past. Post cryopreservation recovery trials using an antimicrobial forced bud development (AFBD) protocol evaluated the ability of selected pretreatments, that improved freeze resistance based on DTA, to improve recovery of dormant budwood of various deciduous tree fruit and nut species. Precryogenic exposure to sucrose solution (5.0 M, 96 hours), desiccation to 30% moisture content (MC) and their combination tested for their efficacy on improving postcryogenic viability in peach, apricot, sweet cherry, little walnut, black walnut, English walnut, apple, and pear. Among the different pretreatments tested, desiccation to 30% MC had the greatest impact on increasing freeze resistance and cryosurvival across most fruit species tested and little walnut. Gradual reduction of MC (40 to 25%) levels increased freeze resistance in peach (R²=0.95) and increased some recovery outcomes (leaf, shoot and bud swell), however, this was not correlated with equal cryorecovery outcomes as severe bud cracking was observed. Overall, our approach linking freeze resistance and preconditioning treatments could help establish efficient species-specific cryopreservation protocols for a number of important temperate woody crops which could be recovered as complete plants by coupling AFBD and plant tissue culture.
During the falling temperatures of autumn, temperate tree-crop species, including almond [Prunus dulcis (Miller) Webb], activate a winter survival strategy called endodormancy to protect against unfavorably cold temperatures. Trees cease vegetative growth and form structures called buds to protect enclosed meristems from the unfavorable environmental conditions, including low temperature and desiccation. Chill accumulation allows the progression from flower bud endodormancy stage to flower bud ecodormancy, a type of dormancy regulated by heat accumulation. Environmental stresses including those caused by climate change significantly affect global crop production. Consequently, climate-resilient crops that can withstand an array of climate changes and environmental perturbations will be required to maintain production. In this context, the adaptation of temperate tree-crop species such as almond to expected future warming climates will depend on the breeding of climate-resilient varieties able to complete endodormancy under warmer and more variable climates. Major breeding challenges will be the appropriate phenotyping and selection of elite seedlings from the required large breeding populations. Genomics, transcriptomics, and epigenetics provide useful tools for the development of improved breeding strategies that are particularly useful when trait evaluation such as endodormancy and ecodormancy is expensive or time-consuming. This chapter reviews the genomic designing for new climate-resilient almond varieties, including promising genetic, genomic, transcriptomic and epigenetic approaches.
This book fully integrates the conventional and biotechnological approaches to fruit crop breeding. Individual chapters are written on a wide variety of species including apple, apricot, blackberry, blueberry, cranberry, cherry, currant, gooseberry, grape, kiwifruit, peach, pear, plum, raspberry and strawberry. For each crop, there is a discussion of their taxonomy and evolution, history of improvement, crossing techniques, evaluation methods, heritability of major traits and germplasm resources, along with the most recent advances in genetic mapping and QTL (quantitative trait loci) analysis, marker assisted breeding, gene cloning, gene expression analysis, regeneration and transformation. Patenting and licensing issues are also covered. This book will be useful in fruit breeding classes and should provide as a springboard for all fruit breeders desiring an update on the latest technologies, horticulturalists who wonder what is being done in fruit breeding and genomicists searching for a way to contribute to fruit breeding efforts.
The paper treats the botanical positions of the new fruit groups of the commercial categories plumcots, pluots and aprium. An appropriate proposal was made for giving concrete taxonomic names and assigning the separate groups of plum-apricot hybrids to concrete systematic ranks. Adopting the results of the analyses by botanists and geneticists will determine and fix the concrete interspecific origin of the hybrids. The phonetically substantiated names of the new botanical species obviously show which of the parent species is positioned as a father parent and which as a mother parent. Thus the plum and the apricot species participating directly in hybridization are specified. It is logical to form the Latin name of each new taxon, rendering an account of the harmonious phonetic sounding, by blending syllables of the mother taxon first, followed by a part of the Latin name of the father taxon, e.g., Armeniaca × Domestica - Armestica.
In this study, the genetic relatedness of 82 walnut genotypes adapted to the North Western Himalayan region of Jammu and Kashmir, India was analyzed by combination of 13 SSR and 20 RAPD primers. A high level of genetic diversity was observed within populations with the number of alleles per locus ranging from one to five in case of SSR primers and two to six in case of RAPD primers, the proportion of polymorphic loci was 100 %, and similarity ranged from 12 % to 79 % with an average of 49 %. Dendrogram showed that all the accessions formed four main clusters with various degree of sub-clustering within the clusters. These results have implications for walnut breeding and conservation.
'Honey Red', a Japanese Plum (Prunus salicina Lindl.), originated from a cross between 'Oishiwase' and 'Santa Rosa' made in 1992 at the National Horticultural Research Institute (NHRI) of the Rural Development Administration (RDA) in Korea. It was first selected as 92Oishiwase*SantaRosa43-2 in 1997 for its high fruit quality with attractive appearance for a very early ripening cultivar. After evaluating the characteristics of the tree and fruit compared with those of 'Oishiwase', a leading Japanese plum in Korea, it was named as 'Honey Red' in 2002. It blooms two days later than 'Oishiwase'. 'Honey Red' has severe self-incompatibility. Therefore, cross-compatible cultivars such as 'Soldam', 'Formosa' and 'Akihime' that bloom simultaneously need to be interplanted in commercial orchards to ensure consistent fruit set. The tree is moderately vigorous and productive. 'Honey Red' is more susceptible than 'Oishiwase' to bacterial leaf spot (Xanthomonas campestris pv. pruni [Smith] Dye). The fruit ripens in early July at Suwon, similar to that of 'Oishiwase'. The fruit is round and skin color is bright red. Fruit weight averages 60 g and soluble solids content 12.5 degrees Brix. The fruit flesh is yellow, marketably firm, sweet and slightly adherent to the pit.
In botanical terms, the word ‘nut’ is used to describe a wide range of seeds, mostly from trees, with a tough, often lignified, seed coat, or shell. True nuts include the chestnut, brazil nut, and hazelnut. In practice, these are usually classified together with certain other so-called nuts, for example the almond, cashew, and peanut, and other seeds, which are all used in similar ways in the diet. Nuts and seeds come from a diverse range of different plants, so their nutritional composition is quite varied, but like most plant seeds they contain a food reserve designed to meet the needs of the developing plant embryo. In many nuts and seeds this is fat, but in others it is starch or other polysaccharides. Therefore, these foods are concentrated sources of dietary energy, as well as sources of protein, unsaturated fatty acids, various micronutrients, and fiber (nonstarch polysaccharides (NSP)).
The present results of classic apple breeding show new multiple resistant cultivars, which possess a high fruit quality and productivity and are highly resistant against the most important diseases and damaging factors in the Central European climatic region. The main breeding aim for resistance is multiple resistance and its stability. The most important fruit, tree and resistance characteristics can be combined by classic methods. Donors are available which transmit these different characteristics well. With classic breeding programmes, new efficient cultivars were developed, which are suitable for modern fruit production. The best example is the new multiple resistant cultivar 'Rebella', which was released for cultivation in 1998. Rebella' has attractive fruits, a high fruit quality and yield and also multiple resistance against scab, mildew, fire blight, bacterial canker, red spider mite, winter frost and spring frosts. The cultivars 'Regine', 'Remo', 'Rewena' and 'Reglindis' carry also 6 or 5 different resistances, combined with high fruit quality and productivity. These multiple resistant cultivars can be the new base of breeding progress to increase the degree of the stable disease resistance in a long term programme. Apple breeding will continue to be successful in the future if classic breeding methods will combined with new molecular methods.
The peach is the third most produced temperate tree fruit species behind apple and pear. This diploid species, Prunus persica, is naturally self-pollinating unlike most of the other cultivated Prunus species. Its center of diversity is in China, where it was domesticated. Starting about 3,000 years ago, the peach was moved from China to all temperate and subtropical climates within the Asian continent and then, more than 2,000 years ago, spread to Persia (present day Iran) via the Silk Road and from there throughout Europe. From Europe it was taken by the Spanish and Portuguese explorers to the Americas. It has an extensive history of breeding that has resulted in scion cultivars with adaptability from cold temperate to tropical zones, a ripening season extending for 6–8 months, and a wide range of fruit and tree characteristics. Peach has also been crossed with species in the Amygdalus and Prunophora subgenera to produce interspecific rootstocks tolerant to soil and disease problems to which P. persica has limited or no resistance. It is the best known temperate fruit species from a genetics perspective and as a model plant has a large array of genomics tools that are beginning to have an impact on the development of new cultivars.
looseness-1Two major cherry species are grown for their fruit, the diploid sweet cherry and the tetraploid sour cherry. For both these species, new cultivars are needed that possess improved fruit quality and disease resistance. Genetic variation exists for most of the desired traits; however, little is known about their inheritance. The one exception is self-compatibility, where the molecular genetic basis has been elucidated in both sweet and sour cherry and molecular markers are available to identify self-compatible individuals in segregating progeny populations. Complete genetic linkage maps in cherry are just now being generated and as a result QTL analyses in cherry lag behind those in other Prunus species, most notably peach. Successful regeneration and transformation of cherry has been reported; however, utilizing this technology for gene function analysis and cultivar generation is still in its infancy.
Will we still be drinking wines made from Pinot Noir and eating McIntosh apples in the 23rd century? Elite grape and apple cultivars, vegetatively propagated for centuries, are highly susceptible to evolving pathogens. In response, growers continually expand their agrochemical weaponry at enormous environmental costs. By contrast, breeders are seeking disease-resistant, tastier alternatives to the handful of dominant cultivars by exploring genetic diversity in these fruits. However, this is a formidable task because consumers cling to ancient cultivars, and breeding long-lived woody perennials is laborious and expensive. Although genomics tools may not solve the former sociocultural dilemma, they can help overcome the latter practical obstacles. Screening seedlings for desirable genetic profiles using molecular techniques reduces the time and high costs associated with growing plants to maturity and evaluating fruit. Such screening is currently in its infancy in apples and grapes, but the adoption of modern DNA sequencing technologies and statistical approaches promises to accelerate cultivar improvement significantly. Here, I describe standard approaches for molecular breeding in apples and grapes, and some of the challenges associated with the collection and analysis of next-generation DNA sequence data. In addition, I urge breeders to establish populations specifically designed for a future of inexpensive genome sequencing.
Plum pox virus, Dideron type (PPV-D), was first detected in Spain in 1984. Since then, it has spread among Japanese plum trees and apricot trees has been extremely rapid in the main producing areas. In Spain, breeding for resistance was the only efficient method for controlling the disease on apricot. Two breeding programmes are currently producing new hybrids resistant to the disease. The main problem encountered by both programmes is the difficult procedure needed for screening the trait that delays the programmes. Nevertheless, more than 8000 seedlings have been produced, two new varieties have been released and several advanced selections are under study. The procedure for screening sharka resistance has varied by techniques and cultivars used which has resulted in different hypotheses about inheritance of the trait. Additionally, several studies on mapping and molecular markers in progress could provide markers for molecular assisted selection that can increase the breeding efficiency.
The paper reviews the taxonomic relationships, morphological distinction, geographical distribution and ecological specificities of the twenty six species recognized (by us) in Amygdalus L. It also surveys the intra-genetic structure in this genus stressing the fact that they fall into five groups of closely related vicarious species: (i) Communis group (9 species), (ii) Orientalis group (6 species), (iii) Sect. Chamaeamygdalus (4 species), (iv) Sect. Spartioides (2 species), and (v) Subgenus Dodecandara (5 species). Within each group, species are separated from one another geographically (in few cases by altitude). The only major exception to such allopatric distribution is found in A. communis L., and this is interpreted as an outcome of domestication. Interspecific sterility barriers are absent, or only weakly developed in Amygdalus, and numerous inter-specific hybrids (particularly between the crop and various wild almond species) have been detected. Therefore most (may be all) wild almond species constitute the primary gene-pool of the cultivated nut crop.
The combined botanical and archaeological evidene points to the Levant countries as the place where the almond was taken into cultivation. Wild forms of A. communis are very likely native only to this area. Also the earliest archaeological signs of almond domestication come from this area.