Browsing by Author "Ghosh, Debasish"

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    Deciphering the role of MIR169d:NF-YA2 module under individual as well as combined drought and heat stress in Arabidopsis
    (Springer Nature Publishing AG, 2024) Gupta, Apoorva; Ghosh, Debasish; Rao, Sombir; Mathur, Saloni
    Plants are often subjected to a combination of abiotic stresses under natural environmental conditions. The response of plants to combined stresses can be very diferent from that to the individual stress. Several regulatory mechanisms work in harmony to maintain plant’s homeostasis during stress conditions. Among them the roles of microRNAs (miRNAs) in combined stresses are beginning to be unravelled. In this study, we evaluated the MIR169d: NF-YA2 target module in individual as well as combined drought and heat stress (HS) in Arabidopsis. We found that MIR169d is highly HS inducible, however, contrary to the reported downregulation of MIR169a/c forms in drought stress in literature, MIR169d is upregulated in drought. Moreover, while MIR169d expression is upregulated during combined stress, the response is less than individual stresses. Further, Arabidopsis plants overexpressing MIR169d or target nf-ya2 knockout mutant plants are more tolerant to both individual as well as combined heat and drought stress as indicated by the higher expression of stress responsive genes and less Trypan blue staining, while plants overexpressing NF-YA2 or those in which miR169defg isoform is sponged up (MIM169defg) are more prone to individual as well as combined heat and drought stress. The MIR169d promoter harbours both heat and drought stress-responsive cis-elements. Assessment of GUS expression in MIR169d-promoter:GUS and NF-YA2-promoter:GUS transgenic lines shows increased and reduced reporter expression in all the three stress conditions as compared to control, respectively. This suggests a stress-induced transcriptional regulation of the MIR169d:NF-YA2 pair. Thus, the MIR169d:NF-YA2 module can be potentially exploited to engineer crops for resistance to multiple abiotic stresses.
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    The MIR169:NF-YA module enhances biomass and yield via ARGOS in Arabidopsis and tomato
    (John Wiley & Sons, 2025) Gupta, Apoorva; Rao, Sombir; Jha, Sarita; Ghosh, Debasish; Virmani, Richa; Shrivastava, Monika; Kumar, Adesh; Sahoo, Laxmipriaya; Das, Jaishri Rubina; Crespi, Martin; Mathur, Saloni
    Molecular links between miRNA: target modules regulating downstream genes for crop maturation/yield are poorly understood. Here, we report that elevated miR169d expression and concomitant reduced NF-YA2 (Nuclear Factor-Y subunit-A) target levels positively regulate vegetative growth and yield in Arabidopsis along with a shorter life cycle. In agreement, increased NF-YA2 levels in (1) NF-YA2-OE (overexpression) lines, (2) miR169d-target-mimicry lines (in which miR169d is chelated), and (3) miR169d-non-cleavable NF-YA2 resistant target lines show the opposite phenotype. Further, we find increased auxin levels in MIR169d-OE and nf-ya2 mutant lines, supporting the enrichment of ‘auxin terms’ in MIR169-OE transcriptome data. We show that ARGOS (auxin-regulated gene involved in organ size) is upregulated in MIR169d-OE due to reduced NF-YA2 repressor levels and that NF-YA2 directly binds the ARGOS promoter. Genetic screens of this module show that neither overexpressing miR169d in an argos mutant background nor the nf-ya2:argos double mutants rescue the argos mutant phenotype, suggesting a parallel pathway of ARGOS regulation via the MIR169:NF-YA2 node, independent of auxin. To assess the translational potential of this module in a crop, we show that Sly-MIR169-OE lines in tomato, having reduced target Sly-NF-YA10 levels, also regulate Sly-ARGOS resulting in early flowering, larger sized fruits, more fruit fresh weight, higher fruit set, early fruiting, and better shelf life than wild-type plants. In contrast, Sly-STTM169 plants inhibited for Sly-miR169 action and having increased levels of Sly-NF-YA10 have a longer life cycle with reduced biomass, decreased fruit set, and an overall reduction in yield. Thus, our findings show a conserved MIR169:NF-YA:ARGOS module which can be applied to crops for addressing future food demands.