Institutional Publications
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Item Global transcriptome and co-expression network analyses reveal cultivar-specific molecular signatures associated with seed development and seed size/weight determination in chickpea(John Wiley & Sons, 2017) Garg, Rohini; Singh, Vikash K.; Rajkumar, Mohan Singh; Kumar, Vinay; Jain, MukeshSeed development is an intricate process regulated via a complex transcriptional regulatory network. To understand the molecular mechanisms governing seed development and seed size/weight in chickpea, we performed a comprehensive analysis of transcriptome dynamics during seed development in two cultivars with contrasting seed size/weight (small seeded, Himchana 1 and large-seeded, JGK 3). Our analysis identified stage-specific expression for a significant proportion (>13%) of the genes. About one-fourth of total genes exhibited significant differential expression in JGK 3 as compared to Himchana 1. We found that different seed development stages can be delineated by modules of co-expressed genes. A comparative analysis revealed differential developmental stage specificity of some modules between the two cultivars. Furthermore, we constructed transcriptional regulatory networks and identified key components determining seed size/weight. The results suggested that extended period of cell division during embryogenesis and higher level of endoreduplication along with more accumulation of storage compounds during maturation determine large seed size/weight. Further, we identified quantitative trait loci-associated candidate genes harboring single nucleotide polymorphisms in the promoter sequences that differentiate small- and large-seeded chickpea cultivars. The results provide a valuable resource to dissect the role of candidate genes governing seed development and seed size/weight in chickpea.Item Characterization of rice homeobox genes, OsHOX22 and OsHOX24, and over-expression of OsHOX24 in transgenic Arabidopsis suggest their role in abiotic stress response(Frontiers Media S.A., 2016) Bhattacharjee, Annapurna; Khurana, Jitendra P.; Jain, MukeshHomeobox transcription factors are well known regulators of plant growth and development. In this study, we carried out functional analysis of two candidate stress-responsive HD-ZIP I class homeobox genes from rice, OsHOX22, and OsHOX24. These genes were highly up-regulated under various abiotic stress conditions at different stages of rice development, including seedling, mature and reproductive stages. The transcript levels of these genes were enhanced significantly in the presence of plant hormones, including abscisic acid (ABA), auxin, salicylic acid, and gibberellic acid. The recombinant full-length and truncated homeobox proteins were found to be localized in the nucleus. Electrophoretic mobility shift assay established the binding of these homeobox proteins with specific DNA sequences, AH1 (CAAT(A/T)ATTG) and AH2 (CAAT(C/G)ATTG). Transactivation assays in yeast revealed the transcriptional activation potential of full-length OsHOX22 and OsHOX24 proteins. Homo- and hetero-dimerization capabilities of these proteins have also been demonstrated. Further, we identified putative novel interacting proteins of OsHOX22 and OsHOX24 via yeast-two hybrid analysis. Over-expression of OsHOX24 imparted higher sensitivity to stress hormone, ABA, and abiotic stresses in the transgenic Arabidopsis plants as revealed by various physiological and phenotypic assays. Microarray analysis revealed differential expression of several stress-responsive genes in transgenic lines as compared to wild-type. Many of these genes were found to be involved in transcriptional regulation and various metabolic pathways. Altogether, our results suggest the possible role of OsHOX22/OsHOX24 homeobox proteins as negative regulators in abiotic stress responses.Item Genome-wide survey and comprehensive expression profiling of Aux/IAA gene family in chickpea and soybean(Frontiers Media S.A., 2015) Singh, Vikash K.; Jain, MukeshAuxin plays a central role in many aspects of plant growth and development. Auxin/Indole-3-Acetic Acid (Aux/IAA) genes cooperate with several other components in the perception and signaling of plant hormone auxin. An investigation of chickpea and soybean genomes revealed 22 and 63 putative Aux/IAA genes, respectively. These genes were classified into six subfamilies on the basis of phylogenetic analysis. Among 63 soybean Aux/IAA genes, 57 (90.5%) were found to be duplicated via whole genome duplication (WGD)/segmental events. Transposed duplication played a significant role in tandem arrangements between the members of different subfamilies. Analysis of Ka/Ks ratio of duplicated Aux/IAA genes revealed purifying selection pressure with restricted functional divergence. Promoter sequence analysis revealed several cis-regulatory elements related to auxin, abscisic acid, desiccation, salt, seed, and endosperm, indicating their role in development and stress responses. Expression analysis of chickpea and soybean Aux/IAA genes in various tissues and stages of development demonstrated tissue/stage specific differential expression. In soybean, at least 16 paralog pairs, duplicated via WGD/segmental events, showed almost indistinguishable expression pattern, but eight pairs exhibited significantly diverse expression patterns. Under abiotic stress conditions, such as desiccation, salinity and/or cold, many Aux/IAA genes of chickpea and soybean revealed differential expression. qRT-PCR analysis confirmed the differential expression patterns of selected Aux/IAA genes in chickpea. The analyses presented here provide insights on putative roles of chickpea and soybean Aux/IAA genes and will facilitate elucidation of their precise functions during development and abiotic stress responses.Item A global view of transcriptome dynamics during flower development in chickpea by deep sequencing(John Wiley & Sons Ltd, 2013) Singh, Vikash K.; Garg, Rohini; Jain, MukeshMeasurement of gene expression can provide important clues about gene function and molecular basis of developmental processes. Here, we have analysed the chickpea transcriptome in vegetative and flower tissues by exploiting the potential of high-throughput sequencing to measure gene expression. We mapped more than 295 million reads to quantify the transcript abundance during flower development. We detected the expression of more than 90% genes in at least one tissue analysed. We found quite a large number of genes were differentially expressed during flower development as compared to vegetative tissues. Further, we identified several genes expressed in a stage-specific manner. Various transcription factor families and metabolic pathways involved in flower development were elucidated. The members of MADS-box family were most represented among the transcription factor genes up-regulated during various stages of flower development. The abundant expression of several well-known genes implicated in flower development in chickpea flower development stages confirmed our results. In addition, we detected the expression specificities of lineage-specific genes during flower development. The expression data presented in this study is the most comprehensive dataset available for chickpea as of now and will serve as resource for unraveling the functions of many specific genes involved in flower development in chickpea and other legumes.Item A draft genome sequence of the pulse crop chickpea (Cicer arietinum L.)(John Wiley & Sons, 2013) Jain, Mukesh; Misra, Gopal; Patel, Ravi K.; Priya, Pushp; Jhanwar, Shalu; Khan, Aamir W.; Shah, Niraj; Singh, Vikas K.; Garg, Rohini; Jeena, Ganga; Yadav, Manju; Kant, Chandra; Sharma, Priyanka; Yadav, Gitanjali; Bhatia, Sabhyata; Tyagi, Akhilesh K.; Chattopadhyay, DebasisCicer arietinum L. (chickpea) is the third most important food legume crop. We have generated the draft sequence of a desi-type chickpea genome using next-generation sequencing platforms, bacterial artificial chromosome end sequences and a genetic map. The 520-Mb assembly covers 70% of the predicted 740-Mb genome length, and more than 80% of the gene space. Genome analysis predicts the presence of 27,571 genes and 210 Mb as repeat elements. The gene expression analysis performed using 274 million RNA-Seq reads identified several tissue-specific and stress-responsive genes. Although segmental duplicated blocks are observed, the chickpea genome does not exhibit any indication of recent whole-genome duplication. Nucleotide diversity analysis provides an assessment of a narrow genetic base within the chickpea cultivars. We have developed a resource for genetic markers by comparing the genome sequences of one wild and three cultivated chickpea genotypes. The draft genome sequence is expected to facilitate genetic enhancement and breeding to develop improved chickpea varieties.Item Microarray analysis reveals overlapping and specific transcriptional responses to different plant hormones in rice(Landes Bioscience, 2012) Garg, Rohini; Tyagi, Akhilesh K.; Jain, MukeshHormones exert pleiotropic effects on plant growth and development throughout the life cycle. Many of these effects are mediated at molecular level via altering gene expression. In this study, we investigated the exogenous effect of plant hormones, including auxin, cytokinin, abscisic acid, ethylene, salicylic acid and jasmonic acid, on the transcription of rice genes at whole genome level using microarray. Our analysis identified a total of 4171 genes involved in several biological processes, whose expression was altered significantly in the presence of different hormones. Further, 28% of these genes exhibited overlapping transcriptional responses in the presence of any two hormones, indicating crosstalk among plant hormones. In addition, we identified genes showing only a particular hormone-specific response, which can be used as hormone-specific markers. The results of this study will facilitate further studies in hormone biology in rice.Item PlantRGS: a web server for the identification of most suitable candidate reference genes for quantitative gene expression studies in plants(Oxford University Press, 2011) Patel, Ravi K.; Jain, MukeshNormalization of quantitative gene expression data with a suitable reference gene is essential for accurate and reliable results. However, the availability and choice of most suitable reference gene(s) showing uniform expression across all the experimental conditions remain a drawback. We have developed a web server, PlantRGS (http://www.nipgr.res.in/PlantRGS), for the identification of most suitable candidate reference gene(s) at the whole-genome level using microarray data for quantitative gene expression studies in plants. Microarray data from more than 11 000 tissue samples for nine plant species have been included in the PlantRGS for meta-analysis. The web server provides a user-friendly graphical user interface-based analysis tool for the identification of most suitable reference genes in the selected plant species under user-defined experimental conditions. Various parameter options and output formats will help users to investigate desired number of most suitable reference genes with wide range of expression levels. Validation of results revealed that novel reference genes identified by the PlantRGS outperforms the traditionally used reference genes in terms of expression stability. We anticipate that the PlantRGS will provide a platform for the identification of most suitable reference gene(s) under given experimental conditions and facilitate quantitative gene expression studies in plants.
