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Item Genome-wide association analysis using multi model approach identified novel associations for plant architectural traits in chickpea germplasm collection(Springer Nature Publishing AG, 2026) Raiya, Rahul; Yadav, Hemant Kumar; Kumar, Kuldeep; Prakash, Nitish Ranjan; Parida, Swarup K.; Bharadwaj, Chellapilla; Hegde, Venkatraman; Tripathi, ShaileshCrop plant architecture dictates plant performance under different ecological conditions and is responsible for its establishment, development, and morphology. It plays an important role in plant breeding for yield optimization, regulating photosynthetic rate and efficiency, utilization of resources, occurrence of pests and diseases, effective mechanical harvesting, space optimization, and improving the quality of plant produce. The subtle changes in the plant’s architecture could help the plant adapt to different ecological niches and are very important, keeping in view the challenges posed due to climate change. A set of 280 diverse genotypes, which included the core collection of chickpea was evaluated during the rabi season of 2021 and 2022. A total of 10 plant architecture related traits, including plant height, first pod height, canopy width, inter-nodal length, and days to flowering were studied and significant variability was observed as per the analysis of variance (ANOVA) and phenotypic descriptors. Diversity based on π and θ estimates suggests the presence of substantial diversity, while Tajima’s D reflects balancing selection due to the abundance of shared alleles. Significant marker trait associations (MTAs) for traits like plant height (PH), first pod height (FDPH) and days to flowering were observed using trait based or BLUP estimates. In total, 97 and 51 MTAs were identified using trait based and BLUP based on multi model GWAS analysis, respectively. Among these 17 were consistent MTAs being present either across the year or were identified using more than one GWAS model. Likewise, 9 consistent MTAs were identified using the BLUP estimates. Interestingly, two genomic regions present on chromosome 5 and 7 were found to harbor multiple MTAs for PH and FPDH. The linkage disequilibrium (LD) block analysis reflects the prevalence of multiple LD blocks in these regions. The allelic effects of the MTAs reflect their additive nature in determining the phenotype. Overall, the MTAs identified in the current study are highly useful for the chickpea breeder in modulating the plant architecture, mainly PH and FPDH.Item 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.Item eQTL-seq: a rapid genome-wide integrative genetical genomics strategy to dissect complex regulatory architecture of gene expression underlying quantitative trait variation in crop plants(Springer Nature Publishing AG, 2024) Mohanty, Jitendra K.; Jha, Uday Chand; Dixit, G. P.; Bharadwaj, Chellapilla; Parida, Swarup K.We developed a combinatorial next generation sequencing (NGS)-based high-throughput expression QTL-seq (eQTL-seq) strategy for rapid elucidation of complex genetic architecture and regulatory pathways of gene expression underlying quantitative trait variation in crop plants. This high-resolution genome-wide integrative genetical genomics strategy assists us to delineate functionally relevant molecular tags (QTLs/eQTLs, genes, master regulators/transcription factors, and alleles) regulating vital agronomic traits in order to expedite genomics-assisted breeding and crop improvement. As a proof-of-concept, the optimized eQTL-seq-led genetical genomics approach was employed in 192 mapping individuals of an intra-specific recombinant inbred line (RIL) population (desi accession ICC 4958 x kabuli accession ICC 12968) with contrasting seed weight trait. This led to identification and mapping of high-resolution major QTLs/eQTLs associated with seed weight based on genome resequence-derived genomic SNP-index (Delta(gSNP-index)), global transcriptome sequence-based expression SNP-index (Delta(eSNP-index)), and relative gene expression (RGE)-index (Delta(RGE-index)). The eQTL-seq scaled down the major seed weight QTLs/eQTLs into the potential candidate gene(s) governing cis- and trans-regulated expression to decipher the gene regulatory modules controlling complex quantitative seed weight trait by deriving global allele-specific gene expression polymorphism in chickpea. Henceforth, the efficacy of NGS-driven integrative eQTL-seq strategy as compared to traditional QTL mapping, fine-mapping (map-based cloning), and QTL-seq approaches that are widely adopted for delineation of candidate genes underlying major QTLs was evident in chickpea. This will further accelerate quantitative dissection of regulatory architecture by decoding the molecular genetic basis of gene expression variation controlling diverse complex phenotypic trait diversity in chickpea and other crop plants as well.Item Broadening the horizon of crop research: a decade of advancements in plant molecular genetics to divulge phenotype governing genes(Springer Nature Publishing AG, 2022) Singh, Ritu; Kumar, Kamal; Bharadwaj, Chellapilla; Verma, Praveen K.The modern crop improvement programs rely heavily on two major steps—trait-associated QTL/gene/marker’s identification and molecular breeding. Thus, it is vital for basic and translational crop research to identify genomic regions that govern the phenotype of interest. Until the advent of next-generation sequencing, the forward-genetic techniques were laborious and time-consuming. Over the last 10 years, advancements in the area of genome assembly, genotyping, large-scale data analysis, and statistical algorithms have led faster identification of genomic variations regulating the complex agronomic traits and pathogen resistance. In this review, we describe the latest developments in genome sequencing and genotyping along with a comprehensive evaluation of the last 10-year headways in forward-genetic techniques that have shifted the focus of plant research from model plants to diverse crops. We have classified the available molecular genetic methods under bulk-segregant analysis-based (QTL-seq, GradedPool-Seq, QTG-Seq, Exome QTL-seq, and RapMap), target sequence enrichment-based (RenSeq, AgRenSeq, and TACCA), and mutation-based groups (MutMap, NIKS algorithm, MutRenSeq, MutChromSeq), alongside improvements in classical mapping and genome-wide association analyses. Newer methods for outcrossing, heterozygous, and polyploid plant genetics have also been discussed. The use of k-mers has enriched the nature of genetic variants which can be utilized to identify the phenotype-causing genes, independent of reference genomes. We envisage that the recent methods discussed herein will expand the repertoire of useful alleles and help in developing high-yielding and climate-resilient crops.Item A chickpea genetic variation map based on the sequencing of 3,366 genomes(Springer Nature Publishing AG, 2021) Varshney, Rajeev K; Roorkiwal, Manish; Sun, Shuai; Bajaj, Prasad; Chitikineni, Annapurna; Thudi, Mahendar; Singh, Narendra P; Du, Xiao; Upadhyaya, Hari D; Khan, Aamir W; Wang, Yue; Garg, Vanika; Fan, Guangyi; Cowling, Wallace A; Crossa, José; Gentzbittel, Laurent; Voss-Fels, Kai Peter; Valluri, Vinod Kumar; Sinha, Pallavi; Singh, Vikas K; Ben, Cécile; Rathore, Abhishek; Punna, Ramu; Singh, Muneendra K; Tar'an, Bunyamin; Bharadwaj, Chellapilla; Yasin, Mohammad; Pithia, Motisagar S; Singh, Servejeet; Soren, Khela Ram; Kudapa, Himabindu; Jarquín, Diego; Cubry, Philippe; Hickey, Lee T; Dixit, Girish Prasad; Thuillet, Anne-Céline; Hamwieh, Aladdin; Kumar, Shiv; Deokar, Amit A; Chaturvedi, Sushil K; Francis, Aleena; Howard, Réka; Chattopadhyay, Debasis; Edwards, David; Lyons, Eric; Vigouroux, Yves; Hayes, Ben J; Wettberg, Eric von; Datta, Swapan K; Yang, Huanming; Nguyen, Henry T; Wang, Jian; Siddique, Kadambot H M; Mohapatra, Trilochan; Bennetzen, Jeffrey L; Xu, Xun; Liu, XinZero hunger and good health could be realized by 2030 through effective conservation, characterization and utilization of germplasm resources1. So far, few chickpea (Cicer arietinum) germplasm accessions have been characterized at the genome sequence level2. Here we present a detailed map of variation in 3,171 cultivated and 195 wild accessions to provide publicly available resources for chickpea genomics research and breeding. We constructed a chickpea pan-genome to describe genomic diversity across cultivated chickpea and its wild progenitor accessions. A divergence tree using genes present in around 80% of individuals in one species allowed us to estimate the divergence of Cicer over the last 21 million years. Our analysis found chromosomal segments and genes that show signatures of selection during domestication, migration and improvement. The chromosomal locations of deleterious mutations responsible for limited genetic diversity and decreased fitness were identified in elite germplasm. We identified superior haplotypes for improvement-related traits in landraces that can be introgressed into elite breeding lines through haplotype-based breeding, and found targets for purging deleterious alleles through genomics-assisted breeding and/or gene editing. Finally, we propose three crop breeding strategies based on genomic prediction to enhance crop productivity for 16 traits while avoiding the erosion of genetic diversity through optimal contribution selection (OCS)-based pre-breeding. The predicted performance for 100-seed weight, an important yield-related trait, increased by up to 23% and 12% with OCS- and haplotype-based genomic approaches, respectively.