Dehydration-responsive Element-binding 2A Research Articles

Variability in drought stress-induced physiological, biochemical responses and expression of DREB2A, NAC4 and HSP70 genes in groundnut (Arachis hypogaea L.)

Drought stress is one of the most important factors of physiological stress and the major constraint on crop productivity which limits plant growth and metabolism. The goal of this work was to study the differential response of groundnut genotypes to drought stress at the physiological, biochemical, and molecular levels during summer in the field. Thirty days old seedlings of six genotypes of groundnut viz. Kadiri 9, Narayani, Dharani, JL24, TPT-3, and Kadiri 6 were subjected to drought stress by withdrawing irrigation for 15 days. The results suggested a significant influence of drought stress on the physiological and biochemical levels in all the groundnut genotypes. A substantial decrease for physiological parameters viz. membrane stability index, chlorophyll stability index, and relative water content was observed under moderate and severe stress conditions compared to control across all genotypes. The high proline accumulating genotypes also exhibited lower lipid peroxidation under all stress periods. In Kadiri 9, Narayani, and Dharani genotypes, the antioxidant enzyme activity of superoxide dismutase, catalase, peroxidase, and glutathione reductase was significantly higher than JL24, TPT-3, and Kadiri 6 genotypes under all stress regimes. Among the genotypes tested, Kadiri 9, Narayani, and Dharani retained higher growth, yield, and seed quality characteristics showing tolerance for drought stress. qPCR analysis revealed stress-responsive existence of the selected genes, heat shock protein 70 (HSP70), dehydration-responsive element binding-2A (DREB2A), and no apical meristem, ATAF1/2, cup-shaped cotyledon 2 (NAC4) with 30 fold increase in the level of expression in Kadiri 9 compared to Kadiri 6.

Assessment of genetic variability and molecular characterization of heat stress tolerant genes in Arachis hypogaea L. through qRT-PCR

Abstract Temperature is the one of the most important environmental factor influencing plant growth and development limiting the crop productivity. Groundnut (Arachis hypogaea L.) is a major crop cultivated in tropical and sub-tropical regions where high temperature stress is a serious constraint for its production. In the present study, groundnut genotypes were screened for thermotolerance using temperature induction response (TIR) technique, where the seedlings were exposed to sub lethal temperature from 38°C-54 °C for 5 h followed by lethal temperature at 58 °C for 3 h. From the 100 diverse genotypes screened, 24 genotypes showed tolerance to high temperature with mean percent seedling survival of 92%, 30 genotypes showed moderate tolerance and 46 genotypes were identified as temperature susceptible compared with checks (100% survival). The expression patterns of selected six groundnut genotypes Kadiri 9, Narayani, Dharani, JL 24, TPT-3 and Kadiri 6 at seedling stage were analyzed under heat stress using Quantitative real-time reverse transcriptase PCR (qRT-PCR). qRT-PCR analysis revealed stress responsive nature of the selected genes. Stress responsive genes such as heat shock protein 90 (HSP90), dehydration responsive element binding-2A (DREB2A) and late embryogenesis abundant4-2 (LEA4-2) showed more than 20–50 fold increase in expression level in selected genotypes.

Salt-responsive ERF1 regulates reactive oxygen species-dependent signaling during the initial response to salt stress in rice.

Early detection of salt stress is vital for plant survival and growth. Still, the molecular processes controlling early salt stress perception and signaling are not fully understood. Here, we identified salt-responsive ERF1 (SERF1), a rice (Oryza sativa) transcription factor (TF) gene that shows a root-specific induction upon salt and hydrogen peroxide (H2O2) treatment. Loss of SERF1 impairs the salt-inducible expression of genes encoding members of a mitogen-activated protein kinase (MAPK) cascade and salt tolerance-mediating TFs. Furthermore, we show that SERF1-dependent genes are H2O2 responsive and demonstrate that SERF1 binds to the promoters of MAPK kinase kinase6 (MAP3K6), MAPK5, dehydration-responsive element bindinG2A (DREB2A), and zinc finger protein179 (ZFP179) in vitro and in vivo. SERF1 also directly induces its own gene expression. In addition, SERF1 is a phosphorylation target of MAPK5, resulting in enhanced transcriptional activity of SERF1 toward its direct target genes. In agreement, plants deficient for SERF1 are more sensitive to salt stress compared with the wild type, while constitutive overexpression of SERF1 improves salinity tolerance. We propose that SERF1 amplifies the reactive oxygen species-activated MAPK cascade signal during the initial phase of salt stress and translates the salt-induced signal into an appropriate expressional response resulting in salt tolerance.

RCD1–DREB2A interaction in leaf senescence and stress responses in Arabidopsis thaliana

Transcriptional regulation of gene expression is one major determinant of developmental control and stress adaptation in virtually all living organisms. In recent years numerous transcription factors controlling various aspects of plant life have been identified. The activity of transcription factors needs to be regulated to prevent unspecific, prolonged or inappropriate responses. The transcription factor DREB2A (DEHYDRATION-RESPONSIVE ELEMENT BINDING 2A) has been identified as one of the main regulators of drought and heat responses, and it is regulated through protein stability. In the present paper we describe evidence that the interaction with RCD1 (RADICAL-INDUCED CELL DEATH 1) contributes to the control of DREB2A under a range of conditions. The interaction is mediated by a novel protein motif in DREB2A and a splice variant of DREB2A which lacks the interaction domain accumulates during heat stress and senescence. In addition RCD1 is rapidly degraded during heat stress, thus our results suggest that removal of RCD1 protein or the loss of the interaction domain in DREB2A appears to be required for proper DREB2A function under stress conditions.