Browsing by Author "Das, Jaishri Rubina"

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Characterization of novel regulators for heat stress tolerance in tomato from Indian sub-continent
(John Wiley & Sons, 2020) Balyan, Sonia; Rao, Sombir; Jha, Sarita; Bansal, Chandni; Das, Jaishri Rubina; Mathur, Saloni
The footprint of tomato cultivation, a cool region crop that exhibits heat stress (HS) sensitivity, is increasing in the tropics/sub‐tropics. Knowledge of novel regulatory hot‐spots from varieties growing in the Indian sub‐continent climatic zones could be vital for developing HS‐resilient crops. Comparative transcriptome‐wide signatures of a tolerant (CLN1621L) and sensitive (CA4) cultivar‐pair shortlisted from a pool of varieties exhibiting variable thermo‐sensitivity using physiological, survival and yield‐related traits revealed redundant to cultivar‐specific HS‐regulation. The antagonistically‐expressing genes encode enzymes and proteins that have roles in plant defense and abiotic stresses. Functional characterization of three antagonistic genes by overexpression and silencing established Solyc09g014280 (Acylsugar acyltransferase) and Solyc07g056570 (Notabilis), that are up‐regulated in tolerant cultivar, as positive regulators of HS‐tolerance and Solyc03g020030 (Pin‐II proteinase inhibitor), that is down‐regulated in CLN1621L, as negative regulator of thermotolerance. Transcriptional assessment of promoters of these genes by SNPs in stress‐responsive cis‐elements and promoter swapping experiments in opposite cultivar background showed inherent cultivar‐specific orchestration of transcription factors in regulating transcription. Moreover, overexpression of three ethylene response transcription factors (ERF.C1/F4/F5) also improved HS‐tolerance in tomato. This study identifies several novel HS‐tolerance genes and provides proof of their utility in tomato thermotolerance.
Cultivar-biased regulation of HSFA7 and HSFB4a govern high-temperature tolerance in tomato
(Springer Nature Publishing AG, 2022) Rao, Sombir; Das, Jaishri Rubina; Balyan, Sonia; Verma, Radhika; Mathur, Saloni
Heat shock factors (HSFs) are at the core of heat stress (HS) response in plants. However, the contribution of HSFs governing the inherent thermo-tolerance mechanism in tomato from sub-tropical hot climates is poorly understood. With the above aim, comparative expression profiles of the HSF family in a HS-tolerant (CLN1621L) and -sensitive cultivars (CA4 and Pusa Ruby) of tomato under HS revealed cultivar-biased regulation of an activator (HSFA7) and a repressor (HSFB4a) class HSF. HSFA7 exhibited strong upregulation while HSFB4a showed downregulation in tolerant tomato cultivar upon HS. Functional characterization of HSFA7 and HSFB4a in a tolerant–sensitive cultivar pair by virus-induced gene silencing (VIGS)-based silencing and transient overexpression established them as a positive and a negative regulator of HS tolerance, respectively. Promoter:GUS reporter assays and promoter sequence analyses suggest heat-mediated transcriptional control of both the HSF genes in the contrasting cultivars. Moreover, degradome data highlighted HSFB4a is a probable target of microRNA Sly-miR4200. Transient in-planta Sly-MIR4200-effector:HSFB4a-reporter assays showed miRNA-dependent target down-regulation. Chelation of miRNA by short-tandem-target-mimic of Sly-miR4200 increased target abundance, highlighting a link between Sly-miR4200 and HSFB4a. This miRNA has induced several folds upon HS in the tolerant cultivar where HSFB4a levels are reduced, thus exhibiting the inverse miR:target expression. Thus, we speculate that the alleviation of HSFB4a and increased HSFA7 levels govern thermo-tolerance in the tolerant cultivar by regulating downstream heat stress-responsive genes.
Exploring the master regulator heat stress transcription factor HSFA1a-mediated transcriptional cascade of HSFs in the heat stress response of tomato
(Springer Nature Publishing AG, 2021) Rao, Sombir; Das, Jaishri Rubina; Mathur, Saloni
The tomato heat stress transcription factor A1a (Sly-HSFA1a) acts as the master regulator of the heat stress (HS) by directly regulating the transcription of Sly-HSFA2. However, it is unclear whether the activation of Sly-HSFA2 alone is sufficient to trigger the entire transcriptional cascade downstream of Sly-HSFA1a. Therefore, the present study aims to delineate the Sly-HSFA1a governed downstream HSFs cascade regulating the tomato heat stress response. The study identified several HSFs with common and specific roles in different HS regimes as well as in HS memory. Furthermore, the study established Sly-HSFA7, Sly-HSFA6b, Sly-HSFA4c, Sly-HSFB1 and Sly-HSFB2b as new downstream targets of SlyHSFA1a during heat stress by using virus-induced-gene-silencing (VIGS) of Sly-HSFA1a. Moreover, the silencing of downstream target Sly-HSFA7 and Sly-HSFB1 revealed the orchestration of downstream transcriptional cascade of HSFs regulated individually or in a synergistic manner by Sly-HSFA1a and Sly-HSFA7 along with co-activator Sly-HSFB1. This complex transcriptional cascade of HSFs sheds light on regulatory mechanisms that enable tomato plants to respond to various heat stress conditions to maintain cellular homeostasis.
HSFA1a: the quarterback of heat stress response and 3D-chromatin organization
(Elsevier B.V., 2023) Das, Jaishri Rubina; Mathur, Saloni
In eukaryotes, the highly complex chromatin exhibits structural dynamism to modulate cellular responses. Recently, Huang et al. have shown a novel role of the heat stress master regulator, HSFA1a, in transiently reorganizing the 3D chromatin to promote distal and proximal enhancer-promoter contacts to regulate stress-responsive genes in tomato.
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.