Institutional Publications
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Item OsiSAP1 overexpression improves water-deficit stress tolerance in transgenic rice by affecting expression of endogenous stress-related genes(Springer, 2014) Dansana, Prasant K.; Kothari, Kamakshi S.; Vij, Shubha; Tyagi, Akhilesh K.OsiSAP1, an A20/AN1 zinc-finger protein, confers water-deficit stress tolerance at different stages of growth by affecting expression of several endogenous genes in transgenic rice. Transgenic lines have been generated from rice constitutively expressing OsiSAP1, an A20/AN1 zinc-finger containing stress-associated protein gene from rice, driven by maize UBIQUITIN gene promoter and evaluated for water-deficit stress tolerance at different stages of growth. Their seeds show early germination and seedlings grow better under water-deficit stress compared to non-transgenic (NT) rice. Leaves from transgenic seedlings showed lesser membrane damage and lipid peroxidation under water-deficit stress. Relatively lower rate of leaf water loss has been observed in detached intact leaves from transgenic plants during late vegetative stage. Delayed leaf rolling and higher relative water content were also observed in transgenic plants under progressive water-deficit stress during reproductive developmental stage. Although reduction in grain yield is observed under unstressed condition, the relative water-deficit stress-induced yield losses are lower in transgenic rice vis-à-vis NT plants thereby resulting in yield loss protection. Transcriptome analysis suggests that overexpression of OsiSAP1 in transgenic rice results in altered expression of several endogenous genes including those coding for transcription factors, membrane transporters, signaling components and genes involved in metabolism, growth and development. A total of 150 genes were found to be more than twofold up-regulated in transgenic rice of which 43 genes are known to be involved in stress response. Our results suggest that OsiSAP1 is a positive regulator of water-deficit stress tolerance in rice.Item Modulation of transcription factor and metabolic pathway genes in response to water-deficit stress in rice(Springer Science, 2011) Ray, Swatismita; Dansana, Prasant K.; Giri, Jitender; Deveshwar, Priyanka; Arora, Rita; Agarwal, Pinky; Khurana, Jitendra P.; Kapoor, Sanjay; Tyagi, Akhilesh K.Water-deficit stress is detrimental for rice growth, development, and yield. Transcriptome analysis of 1-week-old rice (Oryza sativa L. var. IR64) seedling under water-deficit stress condition using Affymetrix 57 K GeneChip® has revealed 1,563 and 1,746 genes to be up- and downregulated, respectively. In an effort to amalgamate data across laboratories, we identified 5,611 differentially expressing genes under varying extrinsic water-deficit stress conditions in six vegetative and one reproductive stage of development in rice. Transcription factors (TFs) involved in ABA-dependent and ABA-independent pathways have been found to be upregulated during water-deficit stress. Members of zinc-finger TFs namely, C₂H₂, C₂C₂, C₃H, LIM, PHD, WRKY, ZF-HD, and ZIM, along with TF families like GeBP, jumonji, MBF1 and ULT express differentially under water-deficit conditions. NAC (NAM, ATAF and CUC) TF family emerges to be a potential key regulator of multiple abiotic stresses. Among the 12 TF genes that are co-upregulated under water-deficit, salt and cold stress conditions, five belong to the NAC TF family. We identified water-deficit stress-responsive genes encoding key enzymes involved in biosynthesis of osmoprotectants like polyols and sugars; amino acid and quaternary ammonium compounds; cell wall loosening and structural components; cholesterol and very long chain fatty acid; cytokinin and secondary metabolites. Comparison of genes responsive to water-deficit stress conditions with genes preferentially expressed during panicle and seed development revealed a significant overlap of transcriptome alteration and pathways.