Chickpea Breeding Programs Research Articles

Genetic diversity and geographical differentiation of Iranian landrace, cultivars, and exotic chickpea lines as revealed by morphological and microsatellite markers.

Assessment of the extent of genetic variability within chickpea is fundamental for chickpea breeding and conservation of genetic resources and is particularly useful as a general guide in the choice of parents for breeding hybrids. To establish genetic diversity among 60 accessions of chickpea comprising landraces, internationally developed improved lines, and cultivars, genetic distances were evaluated using 14 simple sequence repeat markers. These markers showed a high level of polymorphism; a total of 59 different alleles were detected, with a mean of 4.2 alleles per locus. The polymorphic information content (PIC) value ranged from 0.31 to 0.89. All the markers, with the exception of TAA170, TA110, GA34, and Ts35, were considered to be informative (PIC > 0.5), indicating their potential usefulness for cultivar identification. Based on the UNJ clustering method, all accessions were clustered in five groups, which indicated the probable origin and region similarity of Iranian landraces over the other cultivars. It also represents a wide diversity among available germplasm. The result has firmly established that introduction of genetic materials from exotic sources has broadened the genetic base of the national chickpea breeding program. As further implications of the findings, this study can be useful for selective breeding for specific traits and in enhancing the genetic base of breeding programs.

Simple sequence repeat markers associated with agro-morphological traits in chickpea (Cicer arietinum L.)

Chickpea (Cicer arietinum L.), a cool season grain legume, serves as an important cheap source of protein and energy in developing countries, and plays an important role in the enrichment of soil fertility. In order to identify simple sequence repeat (SSR) markers associated with agro-morphological traits in chickpea, 44 genotypes comprising cultigen, landraces, internationally developed improved lines and wild relatives, were phenotyped for several agro-morphological traits in a randomized complete block design with three replications at Urmia Rainfed Research Station. High genetic variability was observed among the chickpea genotypes for the studied agro-morphological traits. In molecular experiment, genetic variability among genotypes was assessed by using SSR markers. One hundred alleles were generated at 16 SSR loci, with a mean number of alleles per locus of 6.25. Using general linear model (GLM) and applying multiple testing corrections, 10 SSR loci associated with the genes controlling the studied agro-morphological traits were identified. Some identified markers were associated with more than one trait. The identified markers could be of great interest in marker assisted selection (MAS) in chickpea breeding programmes.

Efficiency of marker-assisted selection for ascochyta blight in chickpea

SUMMARYThe extent to which markers have been used in chickpea breeding programmes has not been clearly determined. In the current study, phenotypic and marker-assisted selection (MAS) were employed to select blight resistant genotypes, comparing the effectiveness of both methods. The phenotypic evaluation showed that the resistance could be recessive in the material employed. However, the high distorted segregation towards the susceptible parent detected on linkage group four (LG4) could also explain the phenotype distribution of resistance. Phenotypic selection in F2:4and F2:5generations lead to an increase in the frequency of the allele associated with the resistance of the markers CaETR and GAA47, indicating the usefulness of these markers for MAS. The markers TA72 and SCY17 could be also useful for MAS but the high distorted segregation towards the susceptible parent in the region where these markers are located could explain their low effectiveness. The costs associated with phenotypic selection and MAS for ascochyta blight resistance during three cycles of selection are presented in the current study, showing that MAS was more expensive than phenotypic selection. Nevertheless, the use of markers reduced the time taken to select resistant lines. The markers analysed in the current study were useful to select genotypes resistant to ascochyta blight in chickpea breeding programmes, allowing pyramiding genes or quantitative trait loci (QTL) related to different pathotypes. It is recommended that MAS should be employed in early generations of chickpea breeding programmes for the four QTL analysed because this makes it possible to develop populations with a high frequency of the favourable alleles conferring resistance to blight.

Genetic marker discovery, intraspecific linkage map construction and quantitative trait locus analysis of ascochyta blight resistance in chickpea (Cicer arietinum L.)

Ascochyta blight, caused by the fungus Ascochyta rabiei (Pass.) Labr., is a highly destructive disease of chickpea (Cicer arietinum L.) on a global basis, and exhibits considerable natural variation for pathogenicity. Different sources of ascochyta blight resistance are available within the cultivated species, suitable for pyramiding to improve field performance. Robust and closely linked genetic markers are desirable to facilitate this approach. A total of 4,654 simple sequence repeat (SSR) and 1,430 single nucleotide polymorphism (SNP) markers were identified from a chickpea expressed sequence tag (EST) database. Subsets of 143 EST–SSRs and 768 SNPs were further used for validation and subsequent high-density genetic mapping of two intraspecific mapping populations (Lasseter × ICC3996 and S95362 × Howzat). Comparison of the linkage maps to the genome of Medicago truncatula revealed a high degree of conserved macrosynteny. Based on field evaluation of ascochyta blight incidence performed over 2 years, two genomic regions containing resistance determinants were identified in the Lasseter × ICC3996 family. In the S95362 × Howzat population, only one quantitative trait locus (QTL) region was identified for both phenotypic evaluation trials, which on the basis of bridging markers was deduced to coincide with one of the Lasseter × ICC3996 QTLs. Of the two QTL-containing regions identified in this study, one (ab_QTL1) was predicted to be in common with QTLs identified in prior studies, while the other (ab_QTL2) may be novel. Markers in close linkage to ascochyta blight resistance genes that have been identified in this study can be further validated and effectively implemented in chickpea breeding programs.

Morpho-physiological and biochemical alternation responses in different chickpea (Cicer arietinum L.) genotypes under two constructing water regimes

The experiment was conducted to assess the differential morpho-physiological response to stimulated water deficit and to determine the relationship between some of these morphological and physiological traits and yield components of ten chickpea genotypes grown in field under irrigated and rain-fed conditions. Variance analysis of the data showed that the environment was a significant source of variation for all measured characters and genotypes showed significant differences for all measured traits in both environments. In well-watered condition, the highest correlation was belonged to number of seeds per plant and number of pods per plant (P<0.01). The seed yield had highly significant positive correlation with number of seeds per plant (P<0.01) and number of pods per plant (P<0.01). Also, seed yield showed positive significant (P<0.05) correlation with RWC, Na+ and K+ uptake. In water deficit condition high significant positive correlation were observed between grain yields with physiological traits, while in irrigated environment the correlation between grain yields with proline accumulation was not significant. In general, the results suggested that a chickpea cultivar, for increased yield under irrigated conditions, should have maximum number of seeds and pods per plant and under stress conditions should have maximum number of seeds and pods per plant and also keep the high level of RWC, chlorophyll and proline content in their leaves. Thus, identifying these traits as selection criteria in chickpea breeding program may be useful for breeders to introduce suitable drought resistant chickpea cultivars for arid regions.

Efficiency of marker-assisted selection in detection of ascochyta blight resistance in Tunisian chickpea breeding lines

Ascochyta blight (AB) resistance reactions were studied in 23 chickpea cultivars, mainly advanced lines and Tunisian varieties from the Tunisian chickpea breeding program, growing both at two locations and under controlled conditions. Two co-dominant markers both associated with AB resistance were also used in this study; the CaETR marker tightly linked to QT LAR1 in combination with the SCAR SCY17 590 marker linked to QTL AR2 to explore their usefulness in discriminating between resistant and susceptible chickpea genotypes. These two markers contribute efficiently in the selection of new chickpea varieties with better combinations of alleles to ensure durable resistance to AB. The advanced line V10 presenting the resistance allele for CaETR, but being still heterozygous for the SCAR17 590 was characterized as resistant to moderately resistant in field studies and under controlled conditions. This line could be very useful for developing a new variety that is fixed for both resistance alleles and expresses good levels of resistance to AB in different chickpea cropping environments. These markers are very useful in assisting chickpea breeding programs, especially thanks to their robustness, their co-dominance and their utility across different genetic backgrounds.

Impact of Genomic Technologies on Chickpea Breeding Strategies

The major abiotic and biotic stresses that adversely affect yield of chickpea (Cicer arietinum L.) include drought, heat, fusarium wilt, ascochyta blight and pod borer. Excellent progress has been made in developing short-duration varieties with high resistance to fusarium wilt. The early maturity helps in escaping terminal drought and heat stresses and the adaptation of chickpea to short-season environments. Ascochyta blight continues to be a major challenge to chickpea productivity in areas where chickpea is exposed to cool and wet conditions. Limited variability for pod borer resistance has been a major bottleneck in the development of pod borer resistant cultivars. The use of genomics technologies in chickpea breeding programs has been limited, since available genomic resources were not adequate and limited polymorphism was observed in the cultivated chickpea for the available molecular markers. Remarkable progress has been made in the development of genetic and genomic resources in recent years and integration of genomic technologies in chickpea breeding has now started. Marker-assisted breeding is currently being used for improving drought tolerance and combining resistance to diseases. The integration of genomic technologies is expected to improve the precision and efficiency of chickpea breeding in the development of improved cultivars with enhanced resistance to abiotic and biotic stresses, better adaptation to existing and evolving agro-ecologies and traits preferred by farmers, industries and consumers.

Technological properties, antioxidant activity and total phenolic and flavonoid content of pigmented chickpea (Cicer arietinum L.) cultivars

Chickpeas are rich sources of highly nutritious protein and dietary fibre; the health benefits of consuming legumes such as antioxidant activity (AoxA) could be effective for the expansion of their food uses. The technological properties and antioxidant potential of five pigmented chickpea cultivars were evaluated. Protein content of the grains varied from 24.9 to 27.4 g/100 g sample (dw). The cooking time (CT) of the whole grains ranged from 90.5 to 218.5 min; the lowest CT corresponded to Black ICC3761 cultivar. The total phenolic content (TPC) and AoxA [oxygen radical absorbance capacity (ORAC) value] varied from 1.23 to 1.51 mg GAE/g sample (dw) and from 5011 to 5756 μmol TE/100 g sample (dw), respectively; Red ICC13124 showed the highest ORAC value. The differences in technological properties and AoxA among cultivars could be used in chickpea breeding programmes. Chickpea cultivars could contribute significantly to the management and/or prevention of degenerative diseases associated with free radical damage.

Pyramiding of the Resistance to Fe-deficiency Chlorosis and Leaf Miner (Liriomyza cicerina Rond.) in Chickpea (Cicer arietinum L.) by Utation Breedin

Considerable yield losses due to iron (Fe) deficiency chlorosis in chickpea (Cicer arietinum L) may occur when susceptible genotypes are grown in calcareous soils with high pH. The most efficient practical and economical solution to overcome Fe-deficiency chlorosis in chickpea is through the utilization of genetic resistance. In this study, ICC 6119, which is leaf miner [Liriomyza cicerina Rond. (Diptera:Agromyzidae)] resistant but susceptible to Fe-deficiency chlorosis, was irradiated with 200, 300 and 400 Gy gamma rays. Mutated populations were evaluated for resistance to Fe-deficiency chlorosis and leaf miner using a visual scale from M1 to M5 generations. In the M3 generation, one mutant was selected for resistance to Fe-deficiency chlorosis and leaf miner from a single seed descent (SSD) set. Active Fe and chlorophyll content in Fe-efficient mutants were found higher than in the parent genotype ICC 6119. The identified Fe-efficient and leaf miner resistant mutant may be useful in chickpea breeding programs to develop cultivars suitable for a niche environment.

Genetic Diversity and Population Structure of Ethiopian Chickpea (Cicer arietinum L.) Germplasm Accessions from Different Geographical Origins as Revealed by Microsatellite Markers

Genetic diversity and population structure were studied in 155 chickpea (Cicer arietinum L.) entries using 33 polymorphic microsatellite (SSR) markers. Molecular analysis of variance showed variations of 73% within and 27% among populations. Introduced genotypes exhibited highest polymorphism (70.27%) than the landraces (36–57%). Collections from Shewa, Harerge, W. Gojam and S. Gonder regions also showed higher polymorphism (50–57%) than the rest of the local accessions (36–45%). Analyses of pairwise population Nei genetic distance and PhiPT coefficients, expected heterozygosity (He) and unbiased expected heterozygosity (UHe), Shannon’s information index (I) and percent polymorphism (% P) showed existence of high genetic variation between geographical regions. Accessions from adjoining geographical regions mostly showed more genetic similarities than those from origins far isolated apart. This could be associated with the ease and likelihood of inter-regional gene flow and seed movement particularly during times of drought. The 155 entries were grouped into five clusters following analysis of population structure. The first cluster (C1) constituted accessions from Arsi; the second (C2) from Gojam and Gonder; the third (C3) from Harerge and E. and N. Shewa; and the fourth (C4) from W. Shewa, Tigray, and Wello regions. The fifth cluster (C5) was entirely consisted of improved genotypes. Improved genotypes of both Kabuli and Desi types distinctly fell into cluster five (C5) regardless of their difference in seed types. The result has firmly established that introduction of genetic materials from exotic sources has broadened the genetic base of the national chickpea breeding program. Further implications of the findings as regards to chickpea germplasm management and its utilization in breeding program are also discussed.

Genetic Variation and Agronomic Evaluation of Chickpea Cultivars for Grain Yield and Its Components Under Irrigated and Rainfed Growing Conditions

Water deficit is an important factor limiting crop growth all over the world. In order to evaluate genetic variation, heritability and the interrelationship between agronomic traits, twenty chickpea genotypes were cultivated in two separated randomized complete block experiments with three replications under normal irrigated and rainfed conditions. The experiments were carried out at the Agricultural Research Station of Razi University, Kermanshah, Iran, in the 2004-2005 growing season. Under normal conditions, plants were irrigated at stem elongation, pod appearance and pod filling stages. In rainfed conditions, no irrigation treatment was applied. The results revealed that the genotypes S95274 under irrigated and X95TH69 in rainfed conditions had the highest number of pods per plants (NPP), number of seeds per plant (NSP) and grain yield. The genotypes X96TH54 and X95TH69 produced relatively high grain yield compared to other genotypes in both conditions. The highest genotypic and phenotypic coefficients of variation in irrigated (32.61% and 34.67%, respectively) and in rainfed conditions (47.88% and 49.39%, respectively) and also the highest estimation of heritability in both conditions (88% and 93%, respectively) belonged to grain yield. In rainfed growing conditions, the correlations between grain yield and its components were significantly positive while in irrigated conditions grain yield showed significant correlation with NPP (r=0.50) and NSP (r=0.49). According to the results of path analysis, the highest direct (0.99 and 0.73 in irrigated and rainfed conditions, respectively) and indirect effects (0.89 in irrigated and 0.71 in rainfed experiments) on grain yield belonged to NSP and NPP respectively. Based on cluster analysis method, genotypes were classified into three and four groups in irrigated and rainfed conditions, respectively. It can be concluded that the NPP and NSP traits could be used as selection criteria for grain yield improvement in both conditions in chickpea breeding programs.

Quantitative trait loci analysis of seed coat color components for selective breeding in chickpea (Cicer arietinum L.)

Hossain, S., Panozzo, J. F., Pittock, C. and Ford, R. 2011. Quantitative trait loci analysis of seed coat color components for selective breeding in chickpea (Cicer arietinumL.). Can. J. Plant Sci. 91: 49-55. Chickpea (Cicer arietinum L.) is an annual grain legume, grown worldwide for human consumption with the potential to attract premium prices in markets such as India, Bangladesh and southern Asia. The ability to accurately select for seed coat color, an important export quality trait, would greatly benefit chickpea breeding programs. In order to determine the major genomic loci governing the color trait, the color components of CIE L* (luminance), CIE a* (red/green color) and CIE b* (blue/yellow color), C* (chroma or saturation of the color) and h° (hue or purity of the color) were mapped, and associated molecular markers were identified. A linkage map was constructed with 80 SSR markers distributed over 10 linkage groups at an average marker density of 2.8 cM. Two major quantitative trait loci (QTL),...

Characterisation and genetic diversity analysis of selected chickpea cultivars of nine countries using simple sequence repeat (SSR) markers

The genomic DNA profiles of 48 chickpea cultivars released in nine countries and of historical significance to the chickpea breeding programs at ICRISAT and in Ethiopia were evaluated using 48 simple sequence repeat (SSR) markers. Across the cultivars, a total of 504 alleles representing the 48 SSR loci were detected with frequencies ranging from three to 22 (mean 10.5) alleles per locus. The polymorphism information content (PIC) for the SSR markers varied from 0.37 to 0.91 (mean 0.77). A subset of only three highly informative SSR markers (TA176, TA2, TA180) enabled complete discrimination among all 48 chickpea cultivars tested. Hierarchical neighbour-joining UPGMA cluster analysis based on simple matching dissimilarity matrix resolved the 48 cultivars into two major clusters representing desi and kabuli types. These cluster groupings of the cultivars were consistent with the pedigree information available for the cultivars as to the phenotypic classes of chickpea types. Analysis of the temporal patterns of the SSR diversity by classifying 48 chickpea cultivars into four periods of release revealed increasing tendencies in the overall genetic diversity from 0.42 for the earliest varieties developed in the 1970s to 0.62 for those released in the 1980s, and reached a maximum and equivalent level of 0.72 for the varieties developed in the 1990s and 2000s. Overall, the study ascertained that SSRs provide powerful marker tools in revealing genetic diversity and relationships in chickpeas, thereby proving useful for selection of parents in breeding programs and also for DNA fingerprint identification of cultivars.

Quantitative trait loci analysis of seed coat color components for selective breeding in chickpea (Cicer arietinumL.)

Hossain, S., Panozzo, J. F., Pittock, C. and Ford, R. 2011. Quantitative trait loci analysis of seed coat color components for selective breeding in chickpea (Cicer arietinumL.). Can. J. Plant Sci. 91: 49–55. Chickpea (Cicer arietinum L.) is an annual grain legume, grown worldwide for human consumption with the potential to attract premium prices in markets such as India, Bangladesh and southern Asia. The ability to accurately select for seed coat color, an important export quality trait, would greatly benefit chickpea breeding programs. In order to determine the major genomic loci governing the color trait, the color components of CIE L* (luminance), CIE a* (red/green color) and CIE b* (blue/yellow color), C* (chroma or saturation of the color) and h° (hue or purity of the color) were mapped, and associated molecular markers were identified. A linkage map was constructed with 80 SSR markers distributed over 10 linkage groups at an average marker density of 2.8 cM. Two major quantitative trait loci (QTL), which accounted for up to 36 and 49% of the genetic variance and several smaller genetic effects were determined to govern the color components. These were consistent across two differing environments. Once validated, the markers that are close to and flanking these QTL and significantly associated with the minor gene effects will be useful in future color selective breeding programs.

Characterisation of genetic diversity and DNA fingerprinting of Australian chickpea (Cicer arietinum L.) cultivars using MFLP markers

Chickpea (Cicer arietinum L.) is one of the major grain legume crops in the world. In this study, the genetic diversity of 24 Australian chickpea cultivars released between 1987 and 2005 was investigated with microsatellite-anchored fragment length polymorphism (MFLP) DNA markers. Among the cultivars examined, 30 cultivar-specific markers were identified and all were unequivocally identified using the DNA fingerprints developed in this study. Most of the cultivars were grouped into two major clusters; cv. Flipper was separated from the rest based on total character differences of DNA polymorphism. The MFLP approach proved suitable in the analysis of genetic diversity among the chickpea cultivars studied and the genetic relationship identified will be useful for chickpea breeding programs in selecting parent materials.

Osmotic adjustment of chickpea (Cicer arietinum) is not associated with changes in carbohydrate composition or leaf gas exchange under drought

AbstractGenetic differences in osmotic adjustment (OA) have been reported among chickpea (Cicer arietinum) cultivars. In this study eight advanced breeding lines (ABLs) derived from a cross between CTS 60543 (high OA) and Kaniva (low OA) and Tyson (medium OA) and Kaniva, along with the parents, were evaluated for OA, leaf carbohydrate composition and leaf gas exchange under dryland field conditions in India. The water potential (WP) decreased to lower values (less than −2.5 MPa) in Tyson, M 110 and M 86 than in the other genotypes. With decrease in WP, OA increased by 0.5 MPa in Kaniva and CTS 60543 to 1.3 MPa in M 55. As the decrease in WP varied with genotype, when OA was regressed against WP M 39 and M 55 had greater increases in OA with decrease in WP than the remaining nine genotypes, including the parents. As WP decreased, leaf starch content decreased while total soluble sugars, hexoses and sucrose increased: the decrease in starch was much smaller in M 93 and M 129 than in Tyson and M 51, but genotypic differences could not be detected in the increase in total sugars, hexoses or sucrose. The rates of photosynthesis and transpiration decreased as the WP became more negative, but M 129 reached low rates of photosynthesis (2 μmol m−2 s−1) and transpiration at a WP of −1.7 MPa, whereas Tyson reached the same low rate at −2.4 MPa. While OA varied among the chickpea genotypes, the differences were not associated with the changes in carbohydrate composition or the rates of gas exchange at low values of WP. Further, the degree of OA of the 11 genotypes was not the same as when they were selected for differences in OA under rainout shelter conditions in the field in Australia, suggesting that OA may show poor stability depending upon the stress level, location or physiological stage of the plant. This suggests that OA is not a valuable drought‐resistance trait to select for in chickpea breeding programmes.

Identification of diverse germplasm lines for agronomic traits in a chickpea ( Cicer arietinum L.) core collection for use in crop improvement

Utilization of exotic and diverse germplasm is needed to enhance the genetic diversity of cultivars. Genetically diverse lines provide ample opportunity to create favorable gene combinations, and the probability of producing a unique genotype increases in proportion to the number of genes by which the parents differ. Representative core collections (10% of the entire collection) have been suggested as a means to identify useful parents for crop improvement programs. The chickpea core collection (1956 accessions) was evaluated for 14 agronomic traits in two seasons to identify diverse agronomically superior chickpea germplasm. Season (year) and genotypic effects were significant for 13 of the 14 traits, while genotype × season effect was significant for 8 traits. The desi, kabuli, and intermediate type chickpeas differed significantly for days to maturity, basal secondary branches, pods per plant, seed yield, and 100-seed weight. In comparison to controls, 12 accessions flowered early, 15 produced greater seed yield, and 29 had greater 100-seed weight. Based on days to 50% flowering, pods per plant, seed yield, and 100-seed weight, 19 desi, 15 kabuli and 5 intermediate type chickpea germplasm lines originating from 10 countries were selected. The selected desi accessions produced 8.5% more seed yield and had 32% larger seeds than the control cultivar Annigeri while the selected kabuli accessions yielded at par with control L 550 but had 84% larger seeds. The 39 selected accessions and two control cultivars (Annigeri and L 550) were grouped by their first five principal components (PCs) into three clusters. Cluster 1 consisted of early maturing large-seeded kabuli types, cluster 2 early and late maturing desi types, and cluster 3 late maturing intermediate and kabuli types. Clusters 2 and 3 accessions had small to medium sized seeds. These accessions can be used in chickpea breeding programs to develop high yielding desi and kabuli cultivars with a broad genetic base.

Identification of duplicates and fingerprinting of primary and secondary wild annual Cicer gene pools using AFLP markers

Wild annual Cicer gene pools contain valuable germplasm for chickpea improvement programs. Previous research showed that duplication might exist in accessions collected from these gene pools, which would hinder chickpea breeding and related research. AFLP (amplified fragment length polymorphism) markers were used to fingerprint the world collections of the primary and secondary gene pools including C. reticulatum Lad., C. bijugum K.H. Rech., C. judaicum Boiss. and C. pinnatifidum Jaub. et Sp. Duplicates were detected in a total of 24 accessions in both the gene pools, highlighting the necessity to fingerprint the germplasm. Genotypic difference was detected as gene pool specific, species specific and accession specific AFLP markers. These were developed into fingerprinting keys for accession identification between and within species and gene pools. Use of AFLP markers to detect duplicates and to identify accessions is a reliable method which will assist in the characterisation and use of wild annual Cicer germplasm in chickpea improvement programs. We recommend the procedure presented in this paper as a standard approach for the precise genetic identification and characterisation of future world collections of wild Cicer, to keep germplasm integrity and to benefit chickpea breeding and related research programs.

Phosphorus and Micronutrient Nutrition of Chickpea Genotypes in a Multi-Nutrient-Deficient Typic Ustochrept

ABSTRACT The chickpea breeding program in India has not yet considered the genotypic variation in phosphorus (P) efficiency, despite the fact that the largest proportion of chickpea-growing soils are P deficient. Since general P application to chickpea is at sub-optimum levels, efficient P-utilizing genotypes will perform better than others under P-deficient conditions. High levels of P application may induce zinc (Zn) deficiency in plants grown on Zn-deficient soils. Twenty chickpea genotypes were evaluated for their P efficiency at varied levels of added P, and the effect of P levels on Zn, iron (Fe), copper (Cu), and manganese (Mn) nutrition was studied in pot-culture experiments. Three criteria were used for evaluating P efficiency; shoot dry-matter yield without P, P-uptake efficiency (PUPE), and P-utilization efficiency (PUSE). Under P-deficiency conditions (control), the genotypes BG-256, HK-94-134, Phule-G-5, and Vikash produced the highest shoot biomass. However, genotypes that were found to be superior in the absence of P did not perform in a similar way under optimum P supply. Root dry weight showed a highly significant correlation with P uptake at all P levels. In the case of PUPE, genotypes KPG-59 and Pusa-209 were found to be superior to others. With increasing P levels, PUSE declined in all the genotypes. Increasing P up to 13.5 mg kg−1 soil increased Zn concentration, while further increase led to decreased concentration. Genotypes KPG-59, BG-256, RSG-888, and JG-315 showed Zn concentrations below the critical limit of 20 μg Zn g−1 dry weight (DW) at the high level of P application (27.0 mg kg−1). Iron concentration decreased with increasing P levels. Up to 13.5 mg kg−1 P application, Cu concentration increased and thereafter decreased. Manganese concentration gradually increased with the increasing P levels studied. Based on three criteria, BG-256 can be recommended for use in P-deficient conditions and can be good germplasm source material for chickpea-breeding programs for evolving P-efficient genotypes. Results also suggest that when selecting P-efficient genotypes of chickpea, it is essential to apply deficient micronutrients.

Development of ESTs from chickpea roots and their use in diversity analysis of the Cicer genus

BackgroundChickpea is a major crop in many drier regions of the world where it is an important protein-rich food and an increasingly valuable traded commodity. The wild annual Cicer species are known to possess unique sources of resistance to pests and diseases, and tolerance to environmental stresses. However, there has been limited utilization of these wild species by chickpea breeding programs due to interspecific crossing barriers and deleterious linkage drag. Molecular genetic diversity analysis may help predict which accessions are most likely to produce fertile progeny when crossed with chickpea cultivars. While, trait-markers may provide an effective tool for breaking linkage drag. Although SSR markers are the assay of choice for marker-assisted selection of specific traits in conventional breeding populations, they may not provide reliable estimates of interspecific diversity, and may lose selective power in backcross programs based on interspecific introgressions. Thus, we have pursued the development of gene-based markers to resolve these problems and to provide candidate gene markers for QTL mapping of important agronomic traits.ResultsAn EST library was constructed after subtractive suppressive hybridization (SSH) of root tissue from two very closely related chickpea genotypes (Cicer arietinum). A total of 106 EST-based markers were designed from 477 sequences with functional annotations and these were tested on C. arietinum. Forty-four EST markers were polymorphic when screened across nine Cicer species (including the cultigen). Parsimony and PCoA analysis of the resultant EST-marker dataset indicated that most accessions cluster in accordance with the previously defined classification of primary (C. arietinum, C. echinospermum and C. reticulatum), secondary (C. pinnatifidum, C. bijugum and C. judaicum), and tertiary (C. yamashitae, C. chrossanicum and C. cuneatum) gene-pools. A large proportion of EST alleles (45%) were only present in one or two of the accessions tested whilst the others were represented in up to twelve of the accessions tested.ConclusionGene-based markers have proven to be effective tools for diversity analysis in Cicer and EST diversity analysis may be useful in identifying promising candidates for interspecific hybridization programs. The EST markers generated in this study have detected high levels of polymorphism amongst both common and rare alleles. This suggests that they would be useful for allele-mining of germplasm collections for identification of candidate accessions in the search for new sources of resistance to pests / diseases, and tolerance to abiotic stresses.