Publications of NIPGR Scientists
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Item Dissecting the root nodule transcriptome of chickpea (Cicer arietinum L.)(PLOS, 2016) Kant, Chandra; Pradhan, Seema; Bhatia, SabhyataA hallmark trait of chickpea (Cicer arietinum L.), like other legumes, is the capability to convert atmospheric nitrogen (N2) into ammonia (NH3) in symbiotic association with Mesorhizobium ciceri. However, the complexity of molecular networks associated with the dynamics of nodule development in chickpea need to be analyzed in depth. Hence, in order to gain insights into the chickpea nodule development, the transcriptomes of nodules at early, middle and late stages of development were sequenced using the Roche 454 platform. This generated 490.84 Mb sequence data comprising 1,360,251 reads which were assembled into 83,405 unigenes. Transcripts were annotated using Gene Ontology (GO), Cluster of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathways analysis. Differential expression analysis revealed that a total of 3760 transcripts were differentially expressed in at least one of three stages, whereas 935, 117 and 2707 transcripts were found to be differentially expressed in the early, middle and late stages of nodule development respectively. MapMan analysis revealed enrichment of metabolic pathways such as transport, protein synthesis, signaling and carbohydrate metabolism during root nodulation. Transcription factors were predicted and analyzed for their differential expression during nodule development. Putative nodule specific transcripts were identified and enriched for GO categories using BiNGO which revealed many categories to be enriched during nodule development, including transcription regulators and transporters. Further, the assembled transcriptome was also used to mine for genic SSR markers. In conclusion, this study will help in enriching the transcriptomic resources implicated in understanding of root nodulation events in chickpea.Item Global transcriptome analysis of developing chickpea (Cicer arietinum L.) seeds(Frontiers Media S.A., 2014) Pradhan, Seema; Bandhiwal, Nitesh; Shah, Niraj; Kant, Chandra; Gaur, Rashmi; Bhatia, SabhyataUnderstanding developmental processes, especially in non-model crop plants, is extremely important in order to unravel unique mechanisms regulating development. Chickpea (C. arietinum L.) seeds are especially valued for their high carbohydrate and protein content. Therefore, in order to elucidate the mechanisms underlying seed development in chickpea, deep sequencing of transcriptomes from four developmental stages was undertaken. In this study, next generation sequencing platform was utilized to sequence the transcriptome of four distinct stages of seed development in chickpea. About 1.3 million reads were generated which were assembled into 51,099 unigenes by merging the de novo and reference assemblies. Functional annotation of the unigenes was carried out using the Uniprot, COG and KEGG databases. RPKM based digital expression analysis revealed specific gene activities at different stages of development which was validated using Real time PCR analysis. More than 90% of the unigenes were found to be expressed in at least one of the four seed tissues. DEGseq was used to determine differentially expressing genes which revealed that only 6.75% of the unigenes were differentially expressed at various stages. Homology based comparison revealed 17.5% of the unigenes to be putatively seed specific. Transcription factors were predicted based on HMM profiles built using TF sequences from five legume plants and analyzed for their differential expression during progression of seed development. Expression analysis of genes involved in biosynthesis of important secondary metabolites suggested that chickpea seeds can serve as a good source of antioxidants. Since transcriptomes are a valuable source of molecular markers like simple sequence repeats (SSRs), about 12,000 SSRs were mined in chickpea seed transcriptome and few of them were validated. In conclusion, this study will serve as a valuable resource for improved chickpea breeding.Item Large scale in-silico identification and characterization of simple sequence repeats (SSRs) from de novo assembled transcriptome of Catharanthus roseus (L.) G. Don(Springer, 2014) Kumar, Santosh; Shah, Niraj; Garg, Vanika; Bhatia, SabhyataTranscriptomic data of C. roseus offering ample sequence resources for providing better insights into gene diversity: large resource of genic SSR markers to accelerate genomic studies and breeding in Catharanthus . Next-generation sequencing is an efficient system for generating high-throughput complete transcripts/genes and developing molecular markers. We present here the transcriptome sequencing of a 26-day-old Catharanthus roseus seedling tissue using Illumina GAIIX platform that resulted in a total of 3.37 Gb of nucleotide sequence data comprising 29,964,104 reads which were de novo assembled into 26,581 unigenes. Based on similarity searches 58 % of the unigenes were annotated of which 13,580 unique transcripts were assigned 5016 gene ontology terms. Further, 7,687 of the unigenes were found to have Cluster of Orthologous Group classifications, and 4,006 were assigned to 289 Kyoto Encyclopedia of Genes and Genome pathways. Also, 5,221 (19.64 %) of transcripts were distributed to 81 known transcription factor (TF) families. In-silico analysis of the transcriptome resulted in identification of 11,004 SSRs in 26.62 % transcripts from which 2,520 SSR markers were designed which exhibited a non-random pattern of distribution. The most abundant was the trinucleotide repeats (AAG/CTT) followed by the dinucleotide repeats (AG/CT). Location specific analysis of SSRs revealed that SSRs were preferentially associated with the 5'-UTRs with a predicted role in regulation of gene expression. A PCR validation of a set of 48 primers revealed 97.9 % successful amplification, and 76.6 % of them showed polymorphism across different Catharanthus species as well as accessions of C. roseus. In summary, this study will provide an insight into understanding the seedling development and resources for novel gene discovery and SSR development for utilization in marker-assisted selective breeding in C. roseus.
