Institutional Publications

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    OsJAZ9 is involved in water-deficit stress tolerance by regulating leaf width and stomatal density in rice
    (Elsevier B.V., 2021) Singh, Ajit Pal; Mani, Balaji; Giri, Jitender
    Drought stress poses a severe threat to grain yield in rice. Our previous report demonstrated the role of OsJAZ9 in potassium homeostasis by modulating Jasmonic Acid (JA) signalling. While both potassium (K) and JA are known to have an important role in drought stress response, JA's repressor, i.e., JAZs' role in drought stress, remains elusive. Here we report that OsJAZ9 plays a critical role in rice water-deficit stress tolerance via influencing JA and ABA signalling. Overexpression of OsJAZ9 led to the enhanced ABA and JA levels. Our data further revealed that exogenous JA application antagonises the ABA-mediated inhibition of seed germination. Further, OsJAZ9 overexpression reduces leaf width and stomata density, leading to lower leaf transpiration rates than WT. This reduced transpiration and higher K content as osmoticum improved the water-deficit stress tolerance in OsJAZ9 overexpression lines. On the contrary, OsJAZ9 RNAi lines displayed enhanced sensitivity towards water-deficit stress. Our data provide new insights on the role of JA signalling repressors in rice response to water-deficit stress.
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    Genome-wide association study for phosphate deficiency responsive root hair elongation in chickpea
    (Springer Nature Publishing AG, 2020) Kohli, Pawandeep Singh; Verma, Pankaj Kumar; Verma, Rita; Parida, Swarup K.; Thakur, Jitendra K.; Giri, Jitender
    Root hairs (RHs) are single-celled elongated epidermal cells and play a vital role in nutrient absorption, particularly for immobile minerals like phosphorus (P). As an adaptive response to P deficiency, an increase in RH length enhances root-soil contact and absorptive area for P absorption. Genetic variations have been reported for RH length and its response to P deficiency in plants. However, only a few association studies have been conducted to identify genes and genetic loci associated with RH length. Here, we screened desi chickpea accessions for RH length and its plasticity under P deficiency. Further, the genome-wide association study (GWAS) was conducted to identify the genetic loci associated with RH length in P deficient and sufficient conditions. Although high variability was observed in terms of RH length in diverse genotypes, majority of the accessions showed typical response of increase in RH length in low P. Genome-wide association mapping identified many SNPs with significant associations with RH length in P-sufficient and P-deficient conditions. A few candidate genes for RH length in P deficient (SIZ1-like and HAD superfamily protein) and sufficient (RSL2-like and SMAP1-like) conditions were identified which have known roles in RH development and P deficiency response or both. Highly associated loci and candidate genes identified in this study would be useful for genomic-assisted breeding to develop P-efficient chickpea.
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    OsJAZ9 overexpression modulates jasmonic acid biosynthesis and potassium deficiency responses in rice
    (Springer Nature Publishing AG, 2020) Singh, Ajit Pal; Pandey, Bipin K.; Mehra, Poonam; Heitz, Thierry; Giri, Jitender
    Potassium (K) represents up to 10% of the plant’s total dry biomass, and its deficiency makes plants highly susceptible to both abiotic and biotic stresses. K shortage results in the inhibition of root and shoots growth, but the underlying mechanism of this response is unclear. Our RNA-Seq and qPCR analysis suggested leading roles for JA pathway genes under K deficiency in rice. Notably, K deficiency and JA application produced similar phenotypic and transcriptional responses. Here, we integrated molecular, physiological and morphological studies to analyze the role of OsJAZ9 in JA homeostasis and K deficiency responses. We raised OsJAZ9 over-expression, knockdown, transcriptional reporter, translational reporter and C-terminal deleted translational reporter lines in rice to establish the role of JA signaling in K ion homeostasis. JA profiling revealed significantly increased JA-Ile levels in OsJAZ9 OE lines under K deficiency. Furthermore, we established that OsJAZ9 overexpression and knockdown result in K deficiency tolerance and sensitivity, respectively, by modulating various K transporters and root system architecture. Our data provide evidence on the crucial roles of OsJAZ9 for improving K deficiency tolerance in rice by altering JA levels and JA responses.