Publications of NIPGR Scientists
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Item Delineation of genes for a major QTL governing heat stress tolerance in chickpea(Springer Nature Publishing AG, 2024) Mohanty, Jitendra K.; Thakro, Virevol; Yadav, Antima; Nayyar, Harsh; Dixit, Girish P.; Agarwal, Pinky; Parida, Swarup K.; Jha, Uday ChandChickpea (Cicer arietinum) is a cool season grain legume experiencing severe yield loss during heat stress due to the intensifying climate changes and its associated gradual increase of mean temperature. Hence, understanding the genetic architecture regulating heat stress tolerance has emerged as an important trait to be addressed for enhancing yield and productivity of chickpea under heat stress. The present study is intended to identify the major genomic region(s) governing heat stress tolerance in chickpea. For this, an integrated genomics-assisted breeding strategy involving NGS-based high-resolution QTL-seq assay, QTL region-specifc association analysis and molecular haplotyping was deployed in a population of 206 mapping individuals and a diversity panel of 217 germplasm accessions of chickpea. This combinatorial strategy delineated a major 156.8 kb QTL genomic region, which was subsequently narrowed-down to a functional candidate gene CaHSFA5 and its natural alleles associated strongly with heat stress tolerance in chickpea. Superior natural alleles and haplotypes delineated from the CaHSFA5 gene have functional signifcance in regulating heat stress tolerance in chickpea. Histochemical staining, interaction studies along with diferential expression profling of CaHSFA5 and ROS scavenging genes suggest a cross talk between CaHSFA5 with ROS homeostasis pertaining to heat stress tolerance in chickpea. Heterologous gene expression followed by heat stress screening further validated the functional signifcance of CaHSFA5 for heat stress tolerance. The salient outcomes obtained here can have potential to accelerate multiple translational genomic analysis including marker-assisted breeding and gene editing in order to develop high-yielding heat stress tolerant chickpea varieties.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 Functional allele of a MATE gene selected during domestication modulates seed color in chickpea(John Wiley & Sons, 2024) Thakro, Virevol; Varshney, Nidhi; Malik, Naveen; Daware, Anurag; Srivastava, Rishi; Mohanty, Jitendra K; Basu, Udita; Narnoliya, Laxmi; Jha, Uday Chand; Tripathi, Shailesh; Tyagi, Akhilesh K.; Parida, Swarup K.Seed color is one of the key target traits of domestication and artificial selection in chickpeas due to its implications on consumer preference and market value. The complex seed color trait has been well dissected in several crop species; however, the genetic mechanism underlying seed color variation in chickpea remains poorly understood. Here, we employed an integrated genomics strategy involving QTL mapping, high-density mapping, map-based cloning, association analysis, and molecular haplotyping in an inter-specific RIL mapping population, association panel, wild accessions, and introgression lines (ILs) of Cicer gene pool. This delineated a MATE gene, CaMATE23, encoding a Transparent Testa (TT) and its natural allele (8-bp insertion) and haplotype underlying a major QTL governing seed color on chickpea chromosome 4. Signatures of selective sweep and a strong purifying selection reflected that CaMATE23, especially its 8-bp insertion natural allelic variant, underwent selection during chickpea domestication. Functional investigations revealed that the 8-bp insertion containing the third cis-regulatory RY-motif element in the CaMATE23 promoter is critical for enhanced binding of CaFUSCA3 transcription factor, a key regulator of seed development and flavonoid biosynthesis, thereby affecting CaMATE23 expression and proanthocyanidin (PA) accumulation in the seed coat to impart varied seed color in chickpea. Consequently, overexpression of CaMATE23 in Arabidopsis tt12 mutant partially restored the seed color phenotype to brown pigmentation, ascertaining its functional role in PA accumulation in the seed coat. These findings shed new light on the seed color regulation and evolutionary history, and highlight the transcriptional regulation of CaMATE23 by CaFUSCA3 in modulating seed color in chickpea. The functionally relevant InDel variation, natural allele, and haplotype from CaMATE23 are vital for translational genomic research, including marker-assisted breeding, for developing chickpea cultivars with desirable seed color that appeal to consumers and meet global market demand.Item Natural alleles of Mediator subunit genes modulate plant height in chickpea(John Wiley & Sons, 2023) Malik, Naveen; Basu, Udita; Srivastava, Rishi; Daware, Anurag; Ranjan, Rajeev; Sharma, Akash; Thakro, Virevol; Mohanty, Jitendra K.; Jha, Uday Chand; Tripathi, Shailesh; Tyagi, Akhilesh K.; Parida, Swarup K.Plant height (PH) is an important plant architectural trait targeted during Green Revolution to enhance crop yields. Identification of genes and natural alleles governing plant height without compromising agronomic performance can fill the lacuna of knowledge connecting ideal plant architecture with maximum achievable yield in chickpea. Through coherent strategy involving genome-wide association study, QTL/fine mapping, map-based cloning, molecular haplotyping, and downstream functional genomics, the current study identified two Mediator subunit genes namely, CaMED23 and CaMED5b and their derived natural alleles/haplotypes underlying the major QTLs and trans-acting eQTLs regulating plant height in chickpea. Differential accumulation of haplotype-specific transcripts of these two Mediator genes in corresponding haplotype-introgressed near-isogenic lines (NILs) correlates negatively with the plant height trait. Quantitative as well as qualitative estimation based on histology, scanning electron microscopy, and histochemical assay unraveled the reduced lengths and cell sizes of internodes along with compromised lignin levels in dwarf/semi-dwarf chickpea NILs introgressed with superior CaMED23 and CaMED5b gene haplotypes. This observation, supported by global transcriptome profiling-based diminished expression of various phenylpropanoid pathway genes upstream of lignin biosynthesis in dwarf/semi-dwarf NILs, essentially links plant height with lignin accumulation. The identified molecular signatures in the Mediator subunit genes can be efficiently utilized to develop desirable dwarf/semi-dwarf-type chickpea cultivars without affecting their yield per plant via modulating lignin/phenylpropanoid biosynthesis.Item A superior gene allele involved in abscisic acid signaling enhances drought tolerance and yield in chickpea(Oxford University Press, 2023) Thakro, Virevol; Malik, Naveen; Basu, Udita; Srivastava, Rishi; Narnoliya, Laxmi; Daware, Anurag; Varshney, Nidhi; Mohanty, Jitendra K; Bajaj, Deepak; Dwivedi, Vikas; Tripathi, Shailesh; Jha, Uday Chand; Dixit, Girish Prasad; Singh, Ashok K; Tyagi, Akhilesh K.; Upadhyaya, Hari D; Parida, Swarup K.Identifying potential molecular tags for drought tolerance is essential for achieving higher crop productivity under drought stress. We employed an integrated genomics-assisted breeding and functional genomics strategy involving association mapping, fine mapping, map-based cloning, molecular haplotyping and transcript profiling in the introgression lines (ILs)- and near isogenic lines (NILs)-based association panel and mapping population of chickpea (Cicer arietinum). This combinatorial approach delineated a bHLH (basic helix-loop-helix) transcription factor, CabHLH10 (Cicer arietinum bHLH10) underlying a major QTL, along with its derived natural alleles/haplotypes governing yield traits under drought stress in chickpea. CabHLH10 binds to a cis-regulatory G-box promoter element to modulate the expression of RD22 (responsive to desiccation 22), a drought/ABA-responsive gene (via a trans-expression QTL), and two strong yield-enhancement photosynthetic efficiency (PE) genes. This, in turn, upregulates other downstream drought-responsive and abscisic acid signaling genes, as well as yield-enhancing PE genes, thus increasing plant adaptation to drought with reduced yield penalty. We showed that a superior allele of CabHLH10 introgressed into the NILs improved root and shoot biomass and PE, thereby enhancing yield and productivity during drought without compromising agronomic performance. Furthermore, overexpression of CabHLH10 in chickpea and Arabidopsis (Arabidopsis thaliana) conferred enhanced drought tolerance by improving root and shoot agro-morphological traits. These findings facilitate translational genomics for crop improvement and the development of genetically-tailored, climate-resilient, high-yielding chickpea cultivars.Item Salinity stress response and 'omics' approaches for improving salinity stress tolerance in major grain legumes(Springer Nature, 2019) Jha, Uday Chand; Bohra, Abhishek; Jha, Rintu; Parida, Swarup K.Key message Sustaining yield gains of grain legume crops under growing salt-stressed conditions demands a thorough understanding of plant salinity response and more efficient breeding techniques that effectively integrate modern omics knowledge. Abstract Grain legume crops are important to global food security being an affordable source of dietary protein and essential mineral nutrients to human population, especially in the developing countries. The global productivity of grain legume crops is severely challenged by the salinity stress particularly in the face of changing climates coupled with injudicious use of irrigation water and improper agricultural land management. Plants adapt to sustain under salinity-challenged conditions through evoking complex molecular mechanisms. Elucidating the underlying complex mechanisms remains pivotal to our knowledge about plant salinity response. Improving salinity tolerance of plants demand enriching cultivated gene pool of grain legume crops through capitalizing on ‘adaptive traits’ that contribute to salinity stress tolerance. Here, we review the current progress in understanding the genetic makeup of salinity tolerance and highlight the role of germplasm resources and omics advances in improving salt tolerance of grain legumes. In parallel, scope of next generation phenotyping platforms that efficiently bridge the phenotyping–genotyping gap and latest research advances including epigenetics is also discussed in context to salt stress tolerance. Breeding salt-tolerant cultivars of grain legumes will require an integrated “omics-assisted” approach enabling accelerated improvement of salt-tolerance traits in crop breeding programs.
