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Photosynthetic characteristics in wild, cultivated species and interspecific inbred lines of safflower
Abstract
Safflower (Carthamus tinctorius L.), a multipurpose oilseed crop is the only cultivated species in the Carthamus genus. Carthamus spp. have been explored for resistance to biotic and abiotic stresses but not for physiological efficiency. Photosynthetic traits of ten wild and ten cultivated species and six interspecific inbred lines were studied to understand the expression of the photosynthetic traits among them, and for trait introgression from wild species in interspecific derivatives. Relations among some physiological traits in interspecific inbred lines differed from those observed in wild and cultivated species. The high photosynthesis (Pn), low transpiration (E) and high intrinsic water use efficiency (iWUE) could be introgressed from the wild species, C. lanatus and C. turkesthanicus into safflower cultivars. Inheritance of photosynthetic traits from wild to cultivated species indicated that wild species are exploitable for safflower improvement. This study suggests the utilization of wild species for their high Pn, low E and iWUE characteristics for developing abiotic stress-tolerant safflower cultivars.
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Sesame is predominantly cultivated in rainfed and low fertile lands and is frequently exposed to terminal drought. Sesamum species inhabiting dryland ecosystems adaptively diverge from those inhabiting rainfed habitats, and drought-specific traits have a genetic basis. In sesame, traits associated with drought conditions have not been explored to date, yet studies of these traits are needed given that drought is predicted to become more frequent and severe in many parts of the world because of climate change. Here, 76 accessions from the available Indian core set were used to quantify variation in several traits under irrigated (WW) and terminal drought stress (WS) conditions as well as their association with seed yield over two consecutive years. The range of trait variation among the studied genotypes under WW and WS was significant. Furthermore, the traits associated with seed yield under WW and WS differed. The per se performance of the accessions indicated that the expression of most traits was reduced under WS. The correlation analysis revealed that the number of branches, leaf area (LA), leaves dry weight (LDW), number of capsules plant–1, and harvest index (HI) were positively correlated with seed yield under WW and WS, and total dry matter (TDM), plant stem weight, and canopy temperature (CT) were negatively correlated with seed yield under WW and WS, indicating that smaller and cooler canopy genotypes had higher yields. The genotypes IC-131936, IC-204045, IC-204861, IC-205363, IC-205311, and IC-73576 with the highest seed yields were characterized by low canopy temperature, high relative water content, and high harvest index under WS. Phenotypic and molecular diversity analysis was conducted on genotypes along with checks. Phenotypic diversity was assessed using multivariate analysis, whereas molecular diversity was estimated using simple sequence repeat (SSR) loci to facilitate the use of sesame in breeding and genetic mapping. SSRs showed low allelic variation, as indicated by a low average number of alleles (2.31) per locus, gene diversity (0.25), and polymorphism information content (0.22). Cluster analysis (CA) [neighbor-joining (NJ) tree] revealed three major genotypic groups and structure analysis showed 4 populations. The diverse genotypes identified with promising morpho-physiological traits can be used in breeding programs to develop new varieties.
A field experiment was conducted to investigate the effect of deficit moisture stress on eleven sesame genotypes viz., IC-132171, IC-132186, IC-204445, IC-131500, IC-132207, IC-205471, IC-203962, IC-205353, IC-96229, and IC-204966 along with a national check (GT-10). The deficit moisture stress (WS) was imposed for a period of 50–55 days from flowering to physiological maturity. The morphological, physiological, and yield traits under WS significantly decreased in comparison with irrigated conditions (WW). Based on the mean trait performance studied among the genotypes, IC-204966 was found significantly superior with respect to plant height, capsules number, seed weight, total dry matter, leaf area, relative water content and reduced canopy temperature under WS conditions. The correlation analysis of different traits with seed yield indicated that the plant height and number of capsules/plant were highly and positively correlated with seed yield under both WW and WS conditions. The principal component analysis (PCA) revealed that among the traits studied, number of capsules/ plant, total dry matter, stomatal conductance, transpiration rate and fatty acid i.e., palmitic acid were the most important traits that accounted for more than half of the total variation among the sesame genotypes studied. Furthermore, the scatter plot revealed that two genotypes, IC 132,207 and IC 205,471 were stable performers under both stress and irrigated conditions, whereas the performance of check GT-10 varied depending upon conditions.
Photosynthesis is one of the fundamental processes influencing crop growth and productivity. In order to understand better the basis of variation in net photosynthetic rate (PN) and yield potential in rice, two backcross populations derived from Swarna × O. nivara were studied. Gas exchange and chlorophyll fluorescence measurements were taken at flowering stage and data on yield traits at harvest. PN was significantly correlated with stomatal conductance, transpiration rate, mesophyll conductance, carboxylation efficiency, yield per plant (YLDP), and dry mass in both populations. Ten introgression lines (ILs) showed higher PN than their parents. IL 230S showed highest PN with increased YLDP than the remaining ILs. Single marker analysis showed RM514 and RM48 was positively associated with PN and YLDP in popA, whereas RM204 and RM122 in popB. The first 4 principal components contributed 92 and 93% to the total genetic variation in each population, respectively.
Gas exchanges in species and interspecific hybrids of tomato in different environments may contribute to the development and selection of genotypes with a higher tolerance to adverse cultivation conditions. This study aimed to assess the photosynthetic characteristics of wild tomato species and the cultivar Redenção, as well as the respective F1 hybrids of interspecific crosses cultivated under two environments. The experimental design was a randomized block design with three replications and the assessment of six wild accessions, one cultivar, and the respective interspecific hybrids under two environments. At 14, 28, 42, 56, and 70 days after transplanting (DAT), gas exchange characteristics were assessed by means of a portable photosynthesis measurement system. The stomatal density of abaxial and adaxial surfaces of first-order leaflets was estimated under a protected cultivation at 56 DAT. We observed a higher influence of wild tomato species and interspecific hybrids on the assessed characteristics when compared to the cultivation environments. The accession ‘LA-716’ and the hybrid ‘Redenção’ × ‘LA-716’ presented the highest water use efficiency and the accessions ‘PI-127826’ and ‘PI-134417’ and the interspecific hybrids ‘Redenção’ × ‘PI-127826’ and ‘Redenção’ × ‘PI-134417’ presented the highest values of CO2 assimilation, transpiration, instantaneous in vivo carboxylation efficiency of Rubisco, and number of stomata on the abaxial leaflet surface. Thus, the descendants of Solanum habrochaites are an interesting alternative to breeding programs that aim to make advances in obtaining strains that exhibit improvement in their photosynthetic characteristics.
The introduction of genes from wild species is a practice little adopted by breeders for the improvement of commercial crops, although it represents an excellent opportunity to enrich the genetic basis and create new cultivars. In peanut, this practice is being increasingly adopted. In this study we present results of introgression of wild alleles from the wild species Arachis duranensis and A. batizocoi improving photosynthetic traits and yield in a set of lines derived from the cross of an induced allotetraploid and cultivated peanut with selection under water stress. The assays were carried out in greenhouse and field focusing on physiological and agronomic traits. A multivariate model (UPGMA) was adopted in order to classify drought tolerant lines. Several lines showed improved levels of tolerance, with values similar to or greater than the tolerant control. Two BC1F6 lines (53 P4 and 96 P9) were highlighted for good drought-related traits, earliness and pod yield, having better phenotypic profile to the drought tolerant elite commercial cultivar BR1. These lines are good candidates for the creation of peanut cultivars suitable for production in semiarid environments.
Variations in leaf gas-exchange characteristics, PSII activity, leaf pigments, and tuber yield were investigated in seven wild and one cultivated species of Dioscorea from Koraput, India, in order to find out their overall adaptability to the environment. The leaf photosynthetic rate, transpiration, stomatal conductance, water-use efficiency, carboxylation efficiency, and photosynthetic pigments were significantly higher in some wild species compared to the cultivated species. In addition, some wild species showed better photochemical efficiency of PSII, photochemical quenching, and electron transport rate in comparison to cultivated one. Furthermore, leaf dry matter accumulation and tuber yield was also higher in some wild species compared to the cultivated species. Taken together, the wild species, such as D. oppositifolia, D. hamiltonii, and D. pubera, showed the superior photosynthetic efficiency compared to the cultivated D. alata and they could be used for future crop improvement programs.
Water stress can affect the yield in tomato crops and, despite this, there are few types of research aiming to select tomato genotypes resistant to the water stress using physiological parameters. This experiment aimed to study the variables that are related to the gas exchanges and the efficiency in water use, in the selection of tomato genotypes tolerant to water stress. It was done in a greenhouse, measuring 7 x 21 m, in a randomized complete block design, with four replications (blocks), being five genotypes in the F2BC1 generation, which were previously obtained from an interspecific cross between Solanum pennellii versus S. lycopersicum and three check treatments, two susceptible [UFU-22 (pre-commercial line) and cultivar Santa Clara] and one resistant (S. pennellii). At the beginning of flowering, the plants were submitted to a water stress condition, through irrigation suspension. After that CO2 assimilation, internal CO2, stomatal conductance, transpiration, leaf temperature, instantaneous water use efficiency, intrinsic efficiency of water use, instantaneous carboxylation efficiency, chlorophyll a and b, and the potential leaf water (Ψf) were observed. Almost all variables that were analyzed, except CO2 assimilation and instantaneous carboxylation efficiency, demonstrated the superiority of the wild accession, S. pennellii, concerning the susceptible check treatments. The high photosynthetic rate and the low stomatal conductance and transpiration, presented by the UFU22/ F2BC1#2 population, allowed a better water use efficiency. Because of that, these physiological characteristics are promising in the selection of tomato genotypes tolerant to water stress.
To understand the wild Oryza genome effect on photosynthesis and its relation to total dry matter accumulation in an elite rice variety, a set of 40 stable introgression lines (ILs) BC 3 F 8 derived from a cross of Oryza sativa (KMR3) × Oryza rufipogon (WR120) were grown under well watered conditions. Leaf gas exchange measurements and leaf chlorophyll estimates were conducted at the flowering stage. The results revealed significant variations in net photosynthetic rate (Pn), transpiration rate (E), transpiration efficiency (Pn/E) and carboxylation efficiency (Pn/C i). Pn showed significant positive correlation with E, stomatal conductance (g s), Pn/C i and total canopy dry matter. Specific leaf area and leaf thickness were not significantly correlated with Pn. Thirty-seven out of 40 ILs showed higher Pn than KMR3 [11.28 μmol/(m 2 ·s)], and 20 ILs showed higher Pn than WR120 [15.08 μmol/(m 2 ·s)]. The line IL194 showed the highest Pn [21.62 μmol/(m 2 ·s)] with increased total canopy dry matter followed by lines IL381, IL106, IL363-12, IL198, IL86-18 and IL50, which exhibited Pn above 18.0 µmol/(m 2 ·s). The ILs with enhanced Pn are a potential source for developing rice varieties and hybrids with higher biomass and yield.
Carbon balancing within the plant species is an important feature for climatic adaptability. Photosynthesis and respiration traits are directly linked with carbon balance. These features were studied in 20 wild rice accessions Oryza spp., and cultivars. Wide variation was observed within the wild rice accessions for photosynthetic oxygen evolution or photosynthetic rate (A), dark (Rd), and light induced respiration (LIR) rates, as well as stomatal density and number. The mean rate of A varied from 10.49 μmol O2 m−2 s−1 in cultivated species and 13.09 μmol O2 m−2 s−1 in wild spp., The mean Rd is 2.09 μmol O2 m−2 s−1 and 2.31 μmol O2 m−2 s−1 in cultivated and wild spp., respectively. Light induced Respiration (LIR) was found to be almost twice in wild rice spp., (16.75 μmol O2 m−2 s−1) compared to cultivated Oryza spp., Among the various parameters, this study reveals LIR and A as the key factors for positive carbon balance. Stomatal contribution towards carbon balance appears to be more dependent on abaxial surface where several number of stomata are situated. Correlation analysis indicates that Rd and LIR increase with the increase in A. In this study, O. nivara (CR 100100, CR 100097), O. rufipogon (IR 103404) and O. glumaepatula (IR104387) were identified as potential donors which could be used in rice breeding program. Co-ordination between gas exchange and patchiness in stomatal behaviour appears to be important for carbon balance and environmental adaptation of wild rice accessions, therefore, survival under harsh environment. © 2016, Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.
The detection and incorporation of genes from wild plant species provides a means for sustaining genetic improvement in plants cultivated in arid environments. This research measured relative levels of drought tolerance in several genotypes of cultivated (Carthamus tinctorius) and wild (Carthamus oxyacanthus) species. These plants were collected from different regions of Iran and evaluated. Their drought tolerance indices were assessed at three moisture levels. Five drought tolerance indices were calculated based on relative grain yield under drought and normal conditions. There were significant differences between the two species (cultivated and wild). The wild plants sustained more moisture stress tolerance than cultivated species. Increasing water stress levels caused significantly more reductions in the seed yield of cultivated genotypes as compared with wild genotypes. Calculated correlation coefficients revealed that geometric mean productivity (GMP), stress tolerance index (STI) and Harmonic mean (HM) indices are superior criteria for selecting high-yield genotypes under stress and non-stress conditions. Biplot analysis, according to principle component analysis (PCA), indicated that wild genotypes had low yields, but their production was stable when the environment changed. High drought tolerance makes wild Carthamus oxyacanthus safflower a suitable source for transferring drought tolerant genes to cultivated species.
To study whether wild rice species have genes that may increase potential photosynthetic capacities of rice cultivars, we generated BC, populations by reciprocally backcrossing Oryza rufipogon (W630) with O. sativa cv. Nipponbare and IR36; N-BC2 populations and IR-BC2 populations, respectively. We measured the oxygen evolution rates (OER) of single leaves under saturating light and CO2 as the maximum photosynthetic rates and the contents of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and Rubisco activase. Several lines in each BC, population had significantly higher OERs than parental cultivars, and 14similar to25% of plants in BC2 populations had higher OERs than the highest values in parental cultivars. The highest OERs in BC2 populations were about 60% higher than average OERs in parental cultivars. The BC2 populations contained 30-40% more Rubisco than parental cultivars. The Rubisco activase contents in N-BC2 populations were 15-30% lower than that in Nipponbare. Cytoplasms derived from O. rufipogon and O. sativa had different effects on the contents of Rubisco and Rubisco activase particularly in N-BC2 populations. In several lines of each BC2 population the OERs had positive correlations with the contents of Rubisco and/or Rubisco activase. These results suggest that O. rufipogon can be used as a source of germplasm to enhance the photosynthetic capacity of O. sativa.
SYMPOSIA C ereals, dominated by wheat, rice, and maize, provide approximately 50% of human food calories directly and con-siderably more indirectly via feed grains (Tweeten and Thomp-son, 2008). Over the last 20 yr, a period chosen to best estimate current rates of progress without infl uence of earlier periods, the linear rates of yield change for the world (Fig. 1) have been 25kgha –1 yr –1 (wheat), 38 kg ha –1 yr –1 (rice), and 80 kg ha –1 yr –1 (maize). With the exception of maize in some regions, there is no evidence for exponential growth in yield. In fact, relative rates of yield increase are declining and, expressed relative to predicted yield in 2007, are 0.9% yr –1 for wheat, 0.9% yr –1 for rice, and 1.6%yr –1 for maize. Even if these relative rates could be main-tained, various studies suggest they would not prevent real price rises for the three cereals, in the face of projected demand growth to 2050 (Tweeten and Thompson, 2008). Thus there is little doubt that the world needs to continue increasing cereal yields. In this paper we focus on factors determining current rates of yield progress in several key situations (or case studies) and consider ABSTRACT This paper reviews recent progress in wheat (Triticum aestivum L.), rice (Oryza sativa L.), and maize (Zea mays L.) yields resulting from substantial breeding efforts in mostly favorable environments and exam-ines its physiological basis. Breeding and improved agronomy lift potential yield (PY), namely yield with the best variety and management in the absence of man-ageable abiotic and biotic stresses, and PY increase is a key component of progress in farm yield (FY), the other component being closure of the PY to FY gap. Changes in PY and FY are reviewed for several key production regions, namely the United Kingdom and the Yaqui Valley of Mexico for wheat, Japan and Central Luzon in the Philippines for rice, and Iowa and briefl y sub-Saharan Africa for maize. The PY growth rates have fallen and are currently generally no more than 1% per annum and usually much less. The tra-jectory of FY with time often closely parallels PY, but, especially in developing countries, there remain large yield gaps. In at least one instance (maize in Iowa) the gap between PY and FY appears to be closing rapidly. Current genetic progress is linked to increased bio-mass accumulation, and this will remain the way for-ward in the future given the limits to increased harvest index (HI). There is evidence that recent progress is related to increased photosynthesis (e.g., greater radi-ation use effi ciency (RUE) at the canopy level and/or maximum photosynthetic rate P max at saturating irra-diance at the leaf level) before and around anthesis. There is no theoretical reason why this trend cannot continue, especially given the vast genetic resources already found within each crop species. However, it will not be easily or cheaply accomplished, so pros-pects for higher rates of potential yield growth appear to be limited, notwithstanding new molecular tools and claims to the contrary. Closing the yield gap, therefore, becomes more important. Many factors are involved, but breeding can also help farmers achieve this through, for example, improved host plant resistance.
Safflower, Carthamus tinctorius, is a thistle that is grown commercially for the production of oil and birdseed and recently, as a host for the production of transgenic pharmaceutical proteins. C. tinctorius can cross with a number of its wild relatives, creating the possibility of gene flow from safflower to weedy species. In this study we looked at the introgression potential between different members of the genus Carthamus, measured the fitness of the parents versus the F1 hybrids, followed the segregation of a specific transgene in the progeny and tried to identify traits important for adaptation to different environments.
Safflower hybridized and produced viable offspring with members of the section Carthamus and species with chromosome numbers of n = 10 and n = 22, but not with n = 32. The T-DNA construct of a transgenic C. tinctorius line was passed on to the F1 progeny in a Mendelian fashion, except in one specific cross, where it was deleted at a frequency of approximately 21%. Analyzing fitness and key morphological traits like colored seeds, shattering seed heads and the presence of a pappus, we found no evidence of hybrid vigour or increased weediness in the F1 hybrids of commercial safflower and its wild relatives.
Our results suggest that hybridization between commercial safflower and its wild relatives, while feasible in most cases we studied, does not generate progeny with higher propensity for weediness.
Genetic variability, heritability, association and divergence studies in
safflower (Carthamus tinctorius L.) genotypes
Safflower (Carthamus tinctorius L.) is a multipurpose oilseed crop. Fusarium wilt (Fusarium oxysporum f.sp. carthami) is the major damaging disease in safflower. In the present investigation, Fusarium wilt resistance was introgressed from two wild species, Carthamus oxyacantha and Carthamus palaestinus, into susceptible cultivated species through interspecific hybridization. Inheritance of wilt resistance indicated single dominant gene control. Eight simple‐sequence‐repeat (SSR) markers each in (‘Nira’ × C. oxyacantha) and (‘Nira’ × C. palaestinus) were found to be linked to wilt resistance. Marker‐assisted selection for wilt resistance was performed using these markers in F3–F7 generations of both crosses. Six wilt resistant interspecific lines evaluated for 2 years under nondisease conditions have recorded 9%–29% higher seed yield than the high yielding cultivar, ‘A1’. The wilt resistant lines would serve as new sources of resistance to wilt in safflower. The SSR markers linked to wilt resistance would be useful for precise selection of wilt resistance at seedling stage in large segregating populations without attempting screening in artificially inoculated conditions and pyramiding of wilt resistant genes from wild into a common background.
The physiological basis of yield in oilseeds Brassicas needs to be investigated, and the contribution of these traits to its yield is difficult to decipher. Eight cultivars of Brassica belonging to 3 species viz. B. juncea, B. napus and B. carinata - based on significant differences in yield were tested over two years. Net photosynthesis, transpiration, stomatal conductance and water use efficiency were investigated on 3rd and 4th fully expanded leaf on the main stem and related to yield. Average photosynthetic efficiency (umolm-2s-1) was higher in RLC1 (36.1), GSC6(36.3) and PC5 (33.8) cultivars. Impact of environment was inconspicuous. However interactions (GxY) were significant for the studied photosynthetic traits except Pn. Lower transpiration rates were associated with higher water use efficiency in RLC1 (5.69), GSL1 (5.44) and GSC6 (5.40). Positive correlation between SY and Pn (0.385) was recorded for the first time in Brassicas although the magnitude of association was low. Quality mustard cultivar (RLC1, B. juncea) and amongst B. napus GSC6 (canola) and Hyola PAC401 (hybrid, canola) were higher yielders due to relative high Pn, more efficient utilization of water and chlorophyll content. Indeterminate growth habits of the cultivars indicated highest contribution to Pn by leaves during flowering as compared with early siliquae formation. Environment had a profound impact on the yielding ability and the photosynthetic traits.
Plants thought to be typical of 7 species were chosen to represent the various taxa of Carthamus species with 10 pairs of chromosomes. These entities were crossed in all possible combinations and 20 of the possible 21 interspecific hybrids were obtained after 3 seasons of crosses. Analyses of the hybrids included studies of microsporocytes, pollen stainability, achene fertility, rudimentary ovaries, and other morphological characteristics. Pairing of chromosomes at metaphase I indicated no translocations were present in hybrids between C. tenuis from Israel, C. alexandrinus from Egypt, C. glaucus from northern Israel, and C. syriacus from Jordan. Members of this group are assigned the standard arrangement. Hybrids of C. glaucus from Iran, C. glaucus from Syria, and C. dentatus from Turkey always showed a translocation or chromosomal interchange when crossed with any member having the “standard” arrangement. The last 3 species are considered to have the “non-standard” chromosomal arrangement. The parental species used in this study can be regarded as a set of testers which will allow identification of chromosomal differentiation in additional Carthamus materials as they are collected.
We investigated the effects of elevated CO2 concentration ([CO2]), different irrigation regimes, and their interactions on leaf gas exchange, water relations, biomass production, and water use efficiency in tomato plants. In spring 2014, two tomato cultivars (CV1, which is potentially drought tolerant, and CV2 which is potentially heat tolerant) were grown in two separate greenhouse cells at [CO2] of 380 and 590 μmol L−1 (ppm) located at the experimental farm, Taastrup, Denmark. Plants were either irrigated to 18% of volumetric soil water content (FI, full irrigation), or irrigated with 70% water of the fully-irrigated control, delivered to either the whole pot (DI, deficit irrigation) or alternately to only half of the pot (PRD, partial root-zone drying). The experiment was a completed factorial design with four replications per treatment. The two cultivars showed a similar response to soil water deficits, but their water consumption responded differently to high [CO2]. Intrinsic water use efficiency (WUEi, photosynthetic rate/stomatal conductance) and plant water use efficiency (WUEp, aboveground biomass/plant water use) were both significantly increased by reduced irrigation treatments and elevated [CO2], although no significant reduction of stomatal conductance was detected under high [CO2]. There was a positive interaction between CO2 enrichment and water deficits on plant water use efficiency. Root water potential was negetatively affected by reduced irrigation but positively influenced by elevated [CO2], while leaf water potential was significantly decreased only by reduced irrigation. CO2 enrichment increased flower number without affecting fruit number, thereby reducing fruit set. Reduced irrigation in combination with elevated [CO2] caused a significant improvement in plant water use efficiency in both tomato cultivars.
Increase in demand for our primary foodstuffs is outstripping increase in yields, an expanding gap that indicates large potential food shortages by mid-century. This comes at a time when yield improvements are slowing or stagnating as the approaches of the Green Revolution reach their biological limits. Photosynthesis, which has been improved little in crops and falls far short of its biological limit, emerges as the key remaining route to increase the genetic yield potential of our major crops. Thus, there is a timely need to accelerate our understanding of the photosynthetic process in crops to allow informed and guided improvements via in-silico-assisted genetic engineering. Potential and emerging approaches to improving crop photosynthetic efficiency are discussed, and the new tools needed to realize these changes are presented.
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Twenty-one lines representing wild progenitors and cultivated wheats at the diploid, tetraploid, and hexaploid levels were compared during growth under favourable conditions (2l/l6°C, l6-hr days of high intensity natural light, and nonlimiting nutrient supply).
Photosynthesis is a primary trait influencing yield potential, and it should be improved in a yield-potential selection program. Information concerning the genotypic variability and inheritance of photosynthetic efficiency in maize (Zea mays L.) must be obtained before a yield-potential selection program is initiated. We used COâ-exchange rate (CER) of sections from excised leaves to estimate photosynthetic efficiency of 64 random inbred lines of maize derived from Iowa Stiff Stalk Synthetic (BSSS). Our study was conducted for 2 years at one location. Measurements of CER taken during vegetative growth (CER 1) and during grain filling (CER 2) were used to estimate genotypic variances and heritabilities and to calculate selection advances for these two stages of plant development. We also evaluated the possibility of using specific leaf weight and leaf thickness as index traits for CER selection. Results showed that estimates of additive variance were 1.7 and 4.9 times larger than estimates of genotype X environment variance at CER 1 and CER 2, respectively. Narrow-sense heritabilities were 0.58 for CER 1 and 0.80 for CER 2, and realized heritability values were 0.72 (CER 1) and 0.66 (CER 2). A high genotypic correlation between CER at CER 1 and CER 2 indicated selection at either developmental stage would produce nearly identical results. Actual selection advances (15% selection intensity) represented increases of 14 and 22% above population means for CER 1 and CER 2, respectively. Our data suggested that measurement of two replications of four plants/plot grown in two environments would provide most efficient selection advance for inbreds. We concluded that selection for improved CER in BSSS would be possible and that selection must be for CER per se. 1 figure, 5 tables.
Two separate experiments were conducted to investigate the effects of different planting depths and irrigation regimes on the emergence and seedling heights of a cultivated (Carthamus tinctorius L. cv. Arak 2811) and a wild strain (C. oxyacantha Bieb.) of safflower. In the first experiment, three planting depths (0.5, 2.0 and 3.5 cm) and four water levels (6,9,12, and 15 mm) were used. Water was applied only once at the start of the experiment. For Arak 2811, the highest emergence percentage and seedling height were obtained when seeds were planted 0.5 cm deep in the soil and irrigated with the equivalent of 12 mm of rainfall.
In the second experiment, five water levels (3, 6, 9, 12 and 15 mm) were applied at 3-day intervals for a period of 25 days and the planting depth was 0.5 cm. For Arak 2811, the seedlings emerged within 4 to 7 days after the first watering while for the wild strain, the emergence started on the 4th day and continued up to the 17th day. The emergence percentage of the wild safflower was almost half of that of the cultivated strain. However, the emerged wild seedlings were much more resistant to low available water than the seedlings of the cultivated variety of safflower.
Cultivated safflower, Carthamus tinctorius L. (2n = 24), was crossed with the wild species C. lanatus L. (2n = 22). The interspecific hybrid, C. tinctorius × C. lanatus (n t + n 1 = 34), was sterile, forming a mean of 4.85 II/PMC. Colchicine treatment of hybrid seedlings obtained from embryo culture produced a fertile alloploid (2n t + 2n 1 = 68). The alloploid and C. lanatus were highly resistant to Alternaria and Pseudomonas leaf diseases, and Fusarium wilt. C. tinctorius was susceptible to the three pathogens. All safflowers were susceptible to Verticillium da liae although C. lanatus showed less severe symptoms. Disease resistance in the alloploid appeared to be controlled by dominant genes contributed by the genome of C. lanatus.
A survey of 24 wild Oryza accessions identified Oryza australiensis and Oryza rufipogon as potential sources of enhanced photosynthetic rate for introgression into cultivated rice. Photosynthetic capacity per unit leaf area (CER) was associated with leaf N content but not with leaf chlorophyll concentration, flag leaf area, or specific leaf area. Eight fertile, perennial F1 hybrids between O. sativa and O. rufipogon were grown in non-flooded soil, and CER was measured at flowering under saturating light. Two F1 hybrids had greater CER than the average of 26.1μmolm2s−1. The F2 progeny from these hybrids were screened for CER in the field, and segregants with even greater rates of photosynthesis were selected. The basis of high photosynthetic rate in the F2 populations was not leaf thickness or leaf chlorophyll content. One F2 line had exceptionally high CER and stomatal conductance. Broad-sense heritability on an individual plant basis for CER in two F2 populations was 0.44 and 0.37. A highly significant offspring-parent regression of 0.89 for CER was observed in a replicated field evaluation (four blocks, five plants per plot) of 20 vegetatively propagated F2 selections and their F3 seedling progeny. Broad-sense heritability for CER on a plot-mean basis was estimated as 0.74 for both selected F2:3 families and for the selected F2 clones. Genetic resources in the genus Oryza may represent a source of alleles to increase leaf photosynthetic rate in the cultivated species, which we have demonstrated to be a heritable, though environmentally variable, trait in an O. sativa/O. rufipogon population.
An interspecific cross was made between Carthamaus oxyacantha and the cultivated species C. tinctorius to develop a cytoplasmic-genic male sterility (CMS) system in safflower. C. oxyacantha was the donor of sterile cytoplasm. The 3: 1 segregation pattern observed in BC1F2 suggested single gene control with dominance of male-fertility over male-sterility. The information obtained from crossing male sterile X male fertile plants in BC1F3 and BC1F4 generations showed statistically significant single gene (1: 1) segregation for male sterility vs. male fertility. The results demonstrated that C. tinctorius possesses a nuclear fertility restorer gene and that a single dominant allele restored fertility (Rf) in progeny carrying CMS cytoplasm of C. oxyacantha. Male sterility occurred with the homozygous recessive condition (rfrf) in a sterile C. oxyacantha cytoplasm background and not in the normal cytoplasm of C. tinctorius. The genetic background of different restorer lines of C. tinctorius having normal cytoplasm did not effect fertility restoration. The absence of male sterile plants in C. tinctorius populations ruled out the possibility of genetic male sterility. Normal meiosis in F1 and BC1F2 ruled out a cytogenetic basis for the occurrence of male sterility.
Photosynthetic rate (P
N), SPAD value, specific leaf area (SLA), flag leaf area (FLA), and nitrogen content (LN) of genus Oryza were investigated and their correlation was analyzed to assess some of the main photosynthetic traits among different species in the genus Oryza. The results revealed wide variation in these traits. The species O. rufipogon and O. australiensis exhibited maximum photosynthetic rate. Comparison of different types of genomes (diploid: 2n=2x=24; tetraploid: 2n=4x=48) and growth habit (shade- or sun-grown) showed the species of diploid (with genome symbol EE; 2n=2x=24) genomes, with perennial and sun-grown species, had high apparent photosynthesis compared to others. The species with BB/BBCC, shade-grown and the tetraploids showed high SPAD value, and the flag leaf in sun-grown species and diploids were thicker (low SLA) compared with others. However, no significant difference could be noticed among the different types of genomes. Higher leaf area was noticed among the species of CC/CCDD genome, perennial shade-grown species and tetraploids than in others. The variety IR 36 exhibited highest leaf nitrogen concentration. Correlation analysis showed a strong relationship between P
N and leaf nitrogen concentration while no marked relationships were observed among other characteristics. It implies that the species with thick and small leaves with high nitrogen concentration and high photosynthesis evolved better than others. O. rufipogon, with the same genome as O. sativa, could be one of the wild rice resources for elite crop improvement.
Safflower (Carthamus tinctorius L.) is an important oil seed crop with growing importance in many countries around the world. However, safflower fly (Acanthiophilus helianthi Rossi) is one of the main limiting factors to expand the production area of the crop in several countries. Since host plant-resistance is the most efficient method for pest management, we evaluated a germplasm of wild accessions (Carthamus oxyacanthus Bieb.) with mostly brown–black seed coat color along with some white-seeded cultivated safflower genotypes for resistance to safflower fly. The results showed that there was a significant difference between two species for safflower fly damage with all cultivated genotypes being susceptible. However, for the accessions of C. oxyacanthus, a wide range of resistance was observed. In a choice experiment and natural infestation, 35.3–78.9 percent of heads per plant were infested in genotypes of C. tinctorius while for the accessions of C. oxyacanthus this was much smaller and ranged from 1.6 to 13.6%. In addition, percentage of seed yield loss per infested plant was more drastic in cultivated safflower (29.0–72.8%) than the wild accessions (0.0–21.4%). In the no-choice experiment, fly population was dramatically decreased in the wild accessions due to larval mortality and possibility of antibiosis. There was a strong relationship between brown–black seed coat color and resistance to safflower fly indicating the possibility of using this trait in breeding programs of safflower to develop fly-resistant cultivars.
The yield potential (Yp) of a grain crop is the seed mass per unit ground area obtained under optimum growing conditions without weeds, pests and diseases. It is determined by the product of the available light energy and by the genetically determined properties: efficiency of light capture (epsilon i), the efficiency of conversion of the intercepted light into biomass (epsilon c) and the proportion of biomass partitioned into grain (eta). Plant breeding brings eta7 and epsilon i close to their theoretical maxima, leaving epsilon c, primarily determined by photosynthesis, as the only remaining major prospect for improving Yp. Leaf photosynthetic rate, however, is poorly correlated with yield when different genotypes of a crop species are compared. This led to the viewpoint that improvement of leaf photosynthesis has little value for improving Yp. By contrast, the many recent experiments that compare the growth of a genotype in current and future projected elevated [CO2] environments show that increase in leaf photosynthesis is closely associated with similar increases in yield. Are there opportunities to achieve similar increases by genetic manipulation? Six potential routes of increasing epsilon c by improving photosynthetic efficiency were explored, ranging from altered canopy architecture to improved regeneration of the acceptor molecule for CO2. Collectively, these changes could improve epsilon c and, therefore, Y p by c. 50%. Because some changes could be achieved by transgenic technology, the time of the development of commercial cultivars could be considerably less than by conventional breeding and potentially, within 10-15 years.
Molecular differentiation of Fusarium wilt resistant wild and cultivated species of safflower
- K Anjani
- P Ramayya
- M V Kumar
Anjani K, Ramayya P J and Kumar M V 2011. Molecular
differentiation of Fusarium wilt resistant wild and cultivated
species of safflower. International Symposium Genomics of
Crops, Medicinal Plants and Microbes, 29-31 May 2011,
KAU, Thiruvananthapuram.
Cryptic genomic exchange between cultivated safflower (Carthamus tinctorius L.) and wild species C. glaucus, M.Bieb subsp. anatolicus (Bioss). -Proc. of Second National Plant Breeding Congress. Indian Society of Plant Breeders
- K Anjani
- M Pallavi
Anjani K and Pallavi M 2006. Cryptic genomic exchange between
cultivated safflower (Carthamus tinctorius L.) and wild species
C. glaucus, M.Bieb subsp. anatolicus (Bioss). -Proc. of Second
National Plant Breeding Congress. Indian Society of Plant
Breeders; TNAU, Coimbatore, India. pp. 187-193.
Transmission and expression of resistance to Alternaria leaf spot in a cross between Carthamus palaestinus x C. tinctorius. In 'Extended Summary: National Seminar on Changing Global Vegetable Oils Scenario: Issues and Challenges Before India
- K Anjani
- M Pallavi
- R D Prasad
Anjani K, Pallavi M and Prasad R D 2007. Transmission and
expression of resistance to Alternaria leaf spot in a cross
between Carthamus palaestinus x C. tinctorius. In 'Extended
Summary: National Seminar on Changing Global Vegetable
Oils Scenario: Issues and Challenges Before India; Hyderabad,
India, pp. 56-57.
Safflower-Hybridization of crop plants
- P Knowles
Knowles P F 1980. Safflower-Hybridization of crop plants. Fehr
W Rand Hadley H H (Eds.), ASA-CSA, Madison, WI, pp.
535-547.
Extended summaries, National seminar on changing global vegetable oil scenario: issues and challenges before India
- M Pallavi
- R D Prasad
- K Anjani
Pallavi M, Prasad R D and Anjani K 2007. Novel sources of
resistance to Fusarium wilt in Carthamus species. In: Extended
summaries, National seminar on changing global vegetable oil
scenario: issues and challenges before India. 29-31 January
2007, Indian Society of Oilseeds Research, Hyderabad, India.
Sources of resistance to Alternaria leaf spot among Carthamus wild species
- R D Prasad
- K Anjani
Prasad R D and Anjani K 2008. Sources of resistance to Alternaria
leaf spot among Carthamus wild species. In: Safflower:
Unexploited potential and world adaptability, Knights S E and
Potter T D (Eds). Proceedings of the 7th International
Safflower Conference, Wagga New South Wales, Australia.
Correlation of stomatal conductance with photosynthetic capacity of six walnut cultivars from the national assortment
- A Sergiu
- C Emil
- F Marin
Sergiu A, Emil C, Marin F C and Irina A 2014. Correlation of
stomatal conductance with photosynthetic capacity of six
walnut cultivars from the national assortment. South Western
Journal of Horticulture Biology Environment, 5(1): 1-10.