Browsing by Author "Kumar, Tapan"

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Development and characterization of recombinant inbreed lines for seed related traits in chickpea
(CABI, 2015) Kumar, Tapan; Bharadwaj, C.; Alam, Afroz; Singh, Puja; Singhal, Tripti; Chauhan, S.K.; Bhatia, Sabhyata; Sarker, Ashutosh
Seed traits are very important factors in improving yield and productivity of chickpea. However being quantitative in nature, gains through direct selection for these traits particularly for bolder seed size with higher yield were never successful and thus the way forward is to identify QTLs linked to these traits. Such a study requires development of mapping populations segregating for traits of interest. Mapping population of the cross SBD 377 (Desi Bold Type with 100 seed weight 48 g and seed number per plant of 34 per plant) and BGD 112 (Desi small seeded with 100 seed weight of 12-15 g and seed number per plant of 90) was developed at Division of Genetics, IARI. The recombinant inbred line (RILs) has been extensively phenotyped. Contrasting variability exists among the RILs for quantitative characters studied. Plant height ranged from 20 to 70 cm with 1-4 primary branches, 0-23 secondary branches and 7-54 total branches per plant. Number of seeds ranged 5 to 250 seeds per plant and pod number 5-180 per plant. The range of 100 seed weight was 13-50 g. Plant yield varied from 2-69 g. Availability of such a RIL population shall serve as a good base for the QTL analysis.
Development of gene-based markers for use in construction of the chickpea (Cicer arietinum L.) genetic linkage map and identification of QTLs associated with seed weight and plant height
(Springer, 2015) Gupta, Shefali; Kumar, Tapan; Verma, Subodh; Bharadwaj, Chellapilla; Bhatia, Sabhyata
Seed weight and plant height are important agronomic traits and contribute to seed yield. The objective of this study was to identify QTLs underlying these traits using an intra-specific mapping population of chickpea. A F11 population of 177 recombinant inbred lines derived from a cross between SBD377 (100-seed weight- 48 g and plant height- 53 cm) and BGD112 (100-seed weight- 15 g and plant height- 65 cm) was used. A total of 367 novel EST-derived functional markers were developed which included 187 EST-SSRs, 130 potential intron polymorphisms (PIPs) and 50 expressed sequence tag polymorphisms (ESTPs). Along with these, 590 previously published markers including 385 EST-based markers and 205 genomic SSRs were utilized. Of the 957 markers tested for analysis of parental polymorphism between the two parents of the mapping population, 135 (14.64 %) were found to be polymorphic. Of these, 131 polymorphic markers could be mapped to the 8 linkage groups. The linkage map had a total length of 1140.54 cM with an average marker density of 8.7 cM. The map was further used for QTL identification using composite interval mapping method (CIM). Two QTLs each for seed weight, qSW-1 and qSW-2 (explaining 11.54 and 19.24 % of phenotypic variance, respectively) and plant height, qPH-1 and qPH-2 (explaining 13.98 and 12.17 % of phenotypic variance, respectively) were detected. The novel set of genic markers, the intra-specific linkage map and the QTLs identified in the present study will serve as valuable genomic resources in improving the chickpea seed yield using marker-assisted selection (MAS) strategies.
High-density linkage map construction and mapping of seed trait QTLs in chickpea (Cicer arietinum L.) using genotyping-by-sequencing (GBS)
(Nature Publishing Group, 2015) Verma, Subodh; Gupta, Shefali; Bandhiwal, Nitesh; Kumar, Tapan; Bharadwaj, Chellapilla; Bhatia, Sabhyata
This study reports the use of Genotyping-by-Sequencing (GBS) for large-scale SNP discovery and simultaneous genotyping of recombinant inbred lines (RILs) of an intra-specific mapping population of chickpea contrasting for seed traits. A total of 119,672 raw SNPs were discovered, which after stringent filtering revealed 3,977 high quality SNPs of which 39.5% were present in genic regions. Comparative analysis using physically mapped marker loci revealed a higher degree of synteny with Medicago in comparison to soybean. The SNP genotyping data was utilized to construct one of the most saturated intra-specific genetic linkage maps of chickpea having 3,363 mapped positions including 3,228 SNPs on 8 linkage groups spanning 1006.98 cM at an average inter marker distance of 0.33 cM. The map was utilized to identify 20 quantitative trait loci (QTLs) associated with seed traits accounting for phenotypic variations ranging from 9.97% to 29.71%. Analysis of the genomic sequence corresponding to five robust QTLs led to the identification of 684 putative candidate genes whose expression profiling revealed that 101 genes exhibited seed specific expression. The integrated approach utilizing the identified QTLs along with the available genome and transcriptome could serve as a platform for candidate gene identification for molecular breeding of chickpea.
Unraveling the genetics of heat tolerance in chickpea landraces (Cicer arietinum L.) using genome-wide association studies
(Frontiers Media S.A., 2024) Danakumara, Thippeswamy; Kumar, Neeraj; Patil, Basavanagouda Siddanagouda; Kumar, Tapan; Bharadwaj, Chellapilla; Jain, Pradeep Kumar; Nimmy, Manduparambil Subramanian; Joshi, Nilesh; Parida, Swarup Kumar; Bindra, Shayla; Kole, Chittaranjan; Varshney, Rajeev K.
Chickpea, being an important grain legume crop, is often confronted with the adverse effects of high temperatures at the reproductive stage of crop growth, drastically affecting yield and overall productivity. The current study deals with an extensive evaluation of chickpea genotypes, focusing on the traits associated with yield and their response to heat stress. Notably, we observed significant variations for these traits under both normal and high-temperature conditions, forming a robust basis for genetic research and breeding initiatives. Furthermore, the study revealed that yield-related traits exhibited high heritability, suggesting their potential suitability for marker-assisted selection. We carried out single-nucleotide polymorphism (SNP) genotyping using the genotyping-by-sequencing (GBS) method for a genome-wide association study (GWAS). Overall, 27 marker-trait associations (MTAs) linked to yield-related traits, among which we identified five common MTAs displaying pleiotropic effects after applying a stringent Bonferroni-corrected p-value threshold of <0.05 [-log10(p) > 4.95] using the BLINK (Bayesian-information and linkage-disequilibrium iteratively nested keyway) model. Through an in-depth in silico analysis of these markers against the CDC Frontier v1 reference genome, we discovered that the majority of the SNPs were located at or in proximity to gene-coding regions. We further explored candidate genes situated near these MTAs, shedding light on the molecular mechanisms governing heat stress tolerance and yield enhancement in chickpeas such as indole-3-acetic acid-amido synthetase GH3.1 with GH3 auxin-responsive promoter and pentatricopeptide repeat-containing protein, etc. The harvest index (HI) trait was associated with marker Ca3:37444451 encoding aspartic proteinase ortholog sequence of Oryza sativa subsp. japonica and Medicago truncatula, which is known for contributing to heat stress tolerance. These identified MTAs and associated candidate genes may serve as valuable assets for breeding programs dedicated to tailoring chickpea varieties resilient to heat stress and climate change.