Browsing by Author "Bharadwaj, Chellapilla"

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ABC transporter-mediated transport of glutathione conjugates enhances seed yield and quality in chickpea
(American Society of Plant Biologists, 2019) Basu, Udita; Upadhyaya, Hari D.; Srivastava, Rishi; Daware, Anurag; Malik, Naveen; Sharma, Akash; Bajaj, Deepak; Narnoliya, Laxmi; Thakro, Virevol; Kujur, Alice; Tripathi, Shailesh; Bharadwaj, Chellapilla; Hegde, V. S.; Pandey, Ajay K.; Singh, Ashok K.; Tyagi, Akhilesh K.; Parida, Swarup K.
The identification of functionally relevant molecular tags is vital for genomics-assisted crop improvement and enhancing the seed yield, quality and productivity in chickpea. The simultaneous improvement of yield/productivity as well as quality traits often requires pyramiding of multiple genes, which remains a major hurdle given various associated epistatic and pleotropic effects. Unfortunately, no single gene that can improve yield/productivity along with quality and other desirable agromorphological traits is known, hampering the genetic enhancement of chickpea. Using a combinatorial genomics-assisted breeding and functional genomics strategy, this study identified natural alleles and haplotypes of an ABCC3-type transporter gene that regulates seed weight, an important domestication trait, by transcriptional regulation and modulating the transport of glutathione conjugates in seeds of desi and kabuli chickpea. The superior allele/haplotype of this gene introgressed in desi and kabuli near-isogenic lines enhances the seed weight, yield, productivity and multiple desirable plant architecture and seed-quality traits without compromising the agronomic performance. These salient findings can expedite crop improvement endeavors and the development of nutritionally enriched high-yielding cultivars in chickpea.
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.
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, Xin
Zero 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.
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.
Eco TILLING-based association mapping efficiently delineates functionally relevant natural allelic variants of candidate genes governing agronomic traits in chickpea
(Frontiers Media S.A., 2016) Bajaj, Deepak; Srivastava, Rishi; Nath, Manoj; Tripathi, Shailesh; Bharadwaj, Chellapilla; Upadhyaya, Hari D.; Tyagi, Akhilesh K.; Parida, Swarup K.
The large-scale mining and high-throughput genotyping of novel gene-based allelic variants in natural mapping population are essential for association mapping to identify functionally relevant molecular tags governing useful agronomic traits in chickpea. The present study employs an alternative time-saving, non-laborious and economical pool-based EcoTILLING approach coupled with agarose gel detection assay to discover 1133 novel SNP allelic variants from diverse coding and regulatory sequence components of 1133 transcription factor (TF) genes by genotyping in 192 diverse desi and kabuli chickpea accessions constituting a seed weight association panel. Integrating these SNP genotyping data with seed weight field phenotypic information of 192 structured association panel identified eight SNP alleles in the eight TF genes regulating seed weight of chickpea. The associated individual and combination of all SNPs explained 10-15 and 31% phenotypic variation for seed weight, respectively. The EcoTILLING-based large-scale allele mining and genotyping strategy implemented for association mapping is found much effective for a diploid genome crop species like chickpea with narrow genetic base and low genetic polymorphism. This optimized approach thus can be deployed for various genomics-assisted breeding applications with optimal expense of resources in domesticated chickpea. The seed weight-associated natural allelic variants and candidate TF genes delineated have potential to accelerate marker-assisted genetic improvement of chickpea.
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.
Genetic dissection of photosynthetic efficiency traits for enhancing seed yield in chickpea
(John Wiley & Sons, 2019) Basu, Udita; Bajaj, Deepak; Sharma, Akash; Malik, Naveen; Daware, Anurag; Narnoliya, Laxmi; Thakro, Virevol; Upadhyaya, Hari D.; Kumar, Rajendra; Tripathi, Shailesh; Bharadwaj, Chellapilla; Tyagi, Akhilesh K.; Parida, Swarup K.
Understanding the genetic basis of photosynthetic efficiency (PE) contributing to enhanced seed yield per plant (SYP) is vital for genomics-assisted crop improvement of chickpea. The current study employed an integrated genomic strategy involving photosynthesis pathway gene-based association mapping, genome-wide association study, QTL mapping and expression profiling. This identified 16 potential SNP loci linked to major QTLs underlying 16 candidate genes significantly associated with PE and SYP traits in chickpea. The allelic variants were tightly linked to positively interacting QTLs regulating both enhanced PE and SYP traits as exemplified by a chlorophyll A-B binding protein-coding gene. The leaf tissue-specific pronounced up-regulated expression of 16 associated genes in germplasm accessions and homozygous individuals of mapping population was evident. Such combinatorial genomic strategy coupled with gene haplotype-specific association as well as in silico protein-protein interaction study delineated natural alleles and superior haplotypes from a chlorophyll A-B binding protein-coding gene and its interacting gene, Timing of CAB Expression 1, which appear to be most-promising candidates in modulating chickpea PE and SYP traits. These functionally pertinent molecular signatures identified have efficacy to drive marker-assisted selection for developing PE-enriched cultivars with high seed yield in chickpea.
Genetic dissection of plant growth habit in chickpea
(Springer, 2017) Upadhyaya, Hari D.; Bajaj, Deepak; Srivastava, Rishi; Daware, Anurag; Basu, Udita; Tripathi, Shailesh; Bharadwaj, Chellapilla; Tyagi, Akhilesh K.; Parida, Swarup K.
A combinatorial genomics-assisted breeding strategy encompassing association analysis, genetic mapping and expression profiling is found most promising for quantitative dissection of complex traits in crop plants. The present study employed GWAS (genome-wide association study) using 24,405 SNPs (single nucleotide polymorphisms) obtained with genotyping-by-sequencing (GBS) of 92 sequenced desi and kabuli accessions of chickpea. This identified eight significant genomic loci associated with erect (E)/semi-erect (SE) vs. spreading (S)/semi-spreading (SS)/prostrate (P) plant growth habit (PGH) trait differentiation regardless of diverse desi and kabuli genetic backgrounds of chickpea. These associated SNPs in combination explained 23.8% phenotypic variation for PGH in chickpea. Five PGH-associated genes were validated successfully in E/SE and SS/S/P PGH-bearing parental accessions and homozygous individuals of three intra- and interspecific RIL (recombinant inbred line) mapping populations as well as 12 contrasting desi and kabuli chickpea germplasm accessions by selective genotyping through Sequenom MassARRAY. The shoot apical, inflorescence and floral meristems-specific expression, including upregulation (seven-fold) of five PGH-associated genes especially in germplasm accessions and homozygous RIL mapping individuals contrasting with E/SE PGH traits was apparent. Collectively, this integrated genomic strategy delineated diverse non-synonymous SNPs from five candidate genes with strong allelic effects on PGH trait variation in chickpea. Of these, two vernalization-responsive non-synonymous SNP alleles carrying SNF2 protein-coding gene and B3 transcription factor associated with PGH traits were found to be the most promising in chickpea. The SNP allelic variants associated with E/SE/SS/S PGH trait differentiation were exclusively present in all cultivated desi and kabuli chickpea accessions while wild species/accessions belonging to primary, secondary and tertiary gene pools mostly contained prostrate PGH-associated SNP alleles. This indicates strong adaptive natural/artificial selection pressure (Tajima's D 3.15 to 4.57) on PGH-associated target genomic loci during chickpea domestication. These vital leads thus have potential to decipher complex transcriptional regulatory gene function of PGH trait differentiation and for understanding the selective sweep-based PGH trait evolution and domestication pattern in cultivated and wild chickpea accessions adapted to diverse agroclimatic conditions. Collectively, the essential inputs generated will be of profound use in marker-assisted genetic enhancement to develop cultivars with desirable plant architecture of erect growth habit types in chickpea.
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, Shailesh
Crop 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.
Genome-wide development and deployment of informative intron-spanning and intron-length polymorphism markers for genomics-assisted breeding applications in chickpea
(Elsevier B.V., 2016) Srivastava, Rishi; Bajaj, Deepak; Sayal, Yogesh K.; Meher, Prabina K.; Upadhyaya, Hari D.; Kumar, Rajendra; Tripathi, Shailesh; Bharadwaj, Chellapilla; Rao, Atmakuri R.; Parida, Swarup K.
The discovery and large-scale genotyping of informative gene-based markers is essential for rapid delineation of genes/QTLs governing stress tolerance and yield component traits in order to drive genetic enhancement in chickpea. A genome-wide 119169 and 110491 ISM (intron-spanning markers) from 23129 desi and 20386 kabuli protein-coding genes and 7454 in silico InDel (insertion-deletion) (1–45-bp)-based ILP (intron-length polymorphism) markers from 3283 genes were developed that were structurally and functionally annotated on eight chromosomes and unanchored scaffolds of chickpea. A much higher amplification efficiency (83%) and intra-specific polymorphic potential (86%) detected by these markers than that of other sequence-based genetic markers among desi and kabuli chickpea accessions was apparent even by a cost-effective agarose gel-based assay. The genome-wide physically mapped 1718 ILP markers assayed a wider level of functional genetic diversity (19–81%) and well-defined phylogenetics among domesticated chickpea accessions. The gene-derived 1424 ILP markers were anchored on a high-density (inter-marker distance: 0.65 cM) desi intra-specific genetic linkage map/functional transcript map (ICC 4958 × ICC 2263) of chickpea. This reference genetic map identified six major genomic regions harbouring six robust QTLs mapped on five chromosomes, which explained 11–23% seed weight trait variation (7.6–10.5 LOD) in chickpea. The integration of high-resolution QTL mapping with differential expression profiling detected six including one potential serine carboxypeptidase gene with ILP markers (linked tightly to the major seed weight QTLs) exhibiting seed-specific expression as well as pronounced up-regulation especially in seeds of high (ICC 4958) as compared to low (ICC 2263) seed weight mapping parental accessions. The marker information generated in the present study was made publicly accessible through a user-friendly web-resource, “Chickpea ISM-ILP Marker Database”. The designing of multiple ISM and ILP markers (2–5 markers/gene) from an individual gene (transcription factor) with numerous aforementioned desirable genetic attributes can widen the user-preference to select suitable primer combination for simultaneous large-scale assaying of functional allelic variation, natural allelic diversity, molecular mapping and expression profiling of genes among chickpea accessions. This will essentially accelerate the identification of functionally relevant molecular tags regulating vital agronomic traits for genomics-assisted crop improvement by optimal resource expenses in chickpea.
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.
Identifying transcription factor genes associated with yield traits in chickpea
(Springer, 2017) Shimray, Philanim Wungmarong; Bajaj, Deepak; Srivastava, Rishi; Daware, Anurag; Upadhyaya, Hari D.; Kumar, Rajendra; Bharadwaj, Chellapilla; Tyagi, Akhilesh K.; Parida, Swarup K.
Identification of potential transcription factor (TF) gene-derived natural SNP allelic variants regulating pod and seed yield component traits by large-scale mining and genotyping of SNPs in natural germplasm accessions coupled with high-resolution association mapping is vital for understanding the complex genetic architecture of quantitative yield traits in chickpea. In these perspectives, the current study employed a genome-wide GBS (genotyping-by-sequencing) and targeted gene amplicon resequencing-based simultaneous SNP discovery and genotyping assays, which discovered 1611 novel SNPs from 736 TF genes physically mapped on eight chromosomes and unanchored scaffolds of kabuli chickpea genome. These SNPs were structurally and functionally annotated in diverse synonymous and non-synonymous coding as well as non-coding regulatory and intronic sequence components of chickpea TF genes. A high-resolution genetic association analysis was performed by correlating the genotyping information of 1611 TF gene-based SNPs with multi-location/years field phenotyping data of six major pod and seed yield traits evaluated in a constituted association panel (326 desi and kabuli germplasm accessions) of chickpea. This essentially identified 27 TF gene-derived SNPs exhibiting significant association with six major yield traits, namely days to 50% flowering (DF), plant height (PH), branch number (BN), pod number (PN), seed number (SN) and seed weight (SW) in chickpea. These trait-associated SNPs individually and in combination explained 10–23% and 32% phenotypic variation respectively for the studied yield component traits. Interestingly, novel non-synonymous coding SNP allelic variants in five potential candidate TF genes encoding SBP (squamosal promoter binding protein), SNF2 (sucrose non-fermenting 2), GRAS [Gibberellic acid insensitive (GAI)-Repressor of GAI (RGA)-SCARECROW (SCR)], bZIP (basic leucine zipper) and LOB (lateral organ boundaries)-domain proteins associated strongly with DF, PH, BN, PN, SN and SW traits respectively were found most promising in chickpea. The functionally relevant molecular signatures (TFs and natural SNP alleles) delineated by us have potential to accelerate marker-assisted genetic enhancement by developing high pod and seed yielding cultivars of chickpea.
Measurement of respiration and internal oxygen in germinating Cicer arietinum L. seeds using optic microsensor
(Springer, 2017) Pandey, Sonika; Kumari, Aprajita; Bharadwaj, Chellapilla; Gupta, Kapuganti Jagadis
Internal oxygen concentrations vary in different tissues depending on tissue size, developmental stage, and their location. Respiratory rate of tissue also determines internal oxygen levels. For studying various signaling pathways it is essential to establish a correlation between respiration and internal oxygen. Seed germination is associated with increase in respiration which can dictate the internal oxygen and subsequent production of reactive oxygen species. Using optic oxygen microsensor we made an attempt to measure respiratory rate and internal oxygen. We found that microsensor is able to sense internal oxygen and it is also possible to measure oxygen levels in a close vial that contains seeds. Step-by-step protocol is described here along with illustration.
A multiple QTL-Seq strategy delineates potential genomic loci governing flowering time in chickpea
(Frontiers Media S.A., 2017) Srivastava, Rishi; Upadhyaya, Hari D.; Kumar, Rajendra; Daware, Anurag; Basu, Udita; Shimray, Philanim W.; Tripathi, Shailesh; Bharadwaj, Chellapilla; Tyagi, Akhilesh K.; Parida, Swarup K.
Identification of functionally relevant potential genomic loci using an economical, simpler and user-friendly genomics-assisted breeding strategy is vital for rapid genetic dissection of complex flowering time quantitative trait in chickpea. A high-throughput multiple QTL-seq strategy was employed in two inter (Cicer arietinum desi accession ICC 4958 × C reticulatum wild accession ICC 17160)- and intra (ICC 4958 × C. arietinum kabuli accession ICC 8261)-specific RIL mapping populations to identify the major QTL genomic regions governing flowering time in chickpea. The whole genome resequencing discovered 1635117 and 592486 SNPs exhibiting differentiation between early- and late-flowering mapping parents and bulks, constituted by pooling the homozygous individuals of extreme flowering time phenotypic trait from each of two aforesaid RIL populations. The multiple QTL-seq analysis using these mined SNPs in two RIL mapping populations narrowed-down two longer (907.1 kb and 1.99 Mb) major flowering time QTL genomic regions into the high-resolution shorter (757.7 kb and 1.39 Mb) QTL intervals on chickpea chromosome 4. This essentially identified regulatory as well as coding (non-synonymous/synonymous) novel SNP allelic variants from two efl1 (early flowering 1) and GI (GIGANTEA) genes regulating flowering time in chickpea. Interestingly, strong natural allelic diversity reduction (88-91%) of two known flowering genes especially mapped at major QTL intervals as compared to that of background genomic regions (where no flowering time QTLs were mapped; 61.8%) in cultivated vis-à-vis wild Cicer gene pools was evident inferring the significant impact of evolutionary bottlenecks on these loci during chickpea domestication. Higher association potential of coding non-synonymous and regulatory SNP alleles mined from efl1 (36-49%) and GI (33-42%) flowering genes for early and late flowering time differentiation among chickpea accessions was evident. The robustness and validity of two functional allelic variants-containing genes localized at major flowering time QTLs was apparent by their identification from multiple intra-/inter-specific mapping populations of chickpea. The functionally relevant molecular tags delineated can be of immense use for deciphering the natural allelic diversity-based domestication pattern of flowering time and expediting genomics-aided crop improvement to develop early flowering cultivars of chickpea.
Nitric oxide accelerates germination via the regulation of respiration in chickpea
(Oxford University Press, 2019) Pandey, Sonika; Kumari, Aprajita; Shree, Manu; Kumar, Vinod; Singh, Pooja; Bharadwaj, Chellapilla; Loake, Gary J.; Parida, Swarup K.; Masakapalli, Shyam Kumar; Gupta, Kapuganti Jagadis
Seed germination is crucial for the plant life cycle. We investigated the role of nitric oxide (NO) in two chickpea varieties that differ in germination capacity: Kabuli, which has a low rate of germination and germinates slowly, and Desi, which shows improved germination properties. Desi produced more NO than Kabuli and had lower respiratory rates. As a result of the high respiration rates, Kabuli had higher levels of reactive oxygen species (ROS). Treatment with the NO donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP) reduced respiration in Kabuli and decreased ROS levels, resulting in accelerated germination rates. These findings suggest that NO plays a key role in the germination of Kabuli. SNAP increased the levels of transcripts encoding enzymes involved in carbohydrate metabolism and the cell cycle. Moreover, the levels of amino acids and organic acids were increased in Kabuli as a result of SNAP treatment. 1 H-nuclear magnetic resonance analysis revealed that Kabuli has a higher capacity for glucose oxidation than Desi. An observed SNAP-induced increase in 13C incorporation into soluble alanine may result from enhanced oxidation of exogenous [13C]glucose via glycolysis and the pentose phosphate pathway. A homozygous hybrid that originated from a recombinant inbred line population of a cross between Desi and Kabuli germinated faster and had increased NO levels and a reduced accumulation of ROS compared with Kabuli. Taken together, these findings demonstrate the importance of NO in chickpea germination via the control of respiration and ROS accumulation.
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.