Cowpea is sensitive to drought and heat stress, particularly at the reproductive stages of development. Both stresses limit growth and yield, and their effect is more devastating when occurring concurrently. Dehydration-responsive element-binding protein 2A (DREB2A) is an important signaling hub integrating information about two different abiotic stresses, drought and heat. We identified VuDREB2A as a canonical DREB ortholog in cowpea, activating downstream stress-responsive genes by binding to DREs in their promoter. Post-translational modification of a negative regulatory domain (NRD) within the VuDREB2A protein prevents its degradation. Targeted deletion of the NRD produces a stable and constitutively active form VuDREB2A-CA. However, there is very little evidence of its practical utility under field conditions. This study overexpressed the VuDREB2A-CA in a popular cowpea variety and conducted drought- and heat-tolerance experiments across various stress regimes. Transgenic cowpea exhibited significant tolerance with consistently higher yield when exposed to over 30-d drought stress and 3-d exposure to high temperature (28&nbsp;°C˗52&nbsp;°C) without any pleiotropic alterations. The transgenic lines showed higher <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/photosynthetic-efficiency">photosynthetic efficiency</a>, <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/plant-osmotic-adjustment">osmotic adjustment</a>, antioxidant defense, <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/critical-thermal-maximum">thermotolerance</a>, and significantly higher survival and increased biomass than the wild type. Late <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/embryogenesis">embryogenesis</a> abundant 5, <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/heat-shock-protein-70">heat shock protein 70</a>, <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/dehydrin">dehydrin</a>, mitogen-activated protein kinase 2/4, <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/isoflavonoid">isoflavonoid</a> <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/reductase">reductase</a>, and myoinositol phosphate <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/synthase">synthase</a> were upregulated in transgenic lines under drought and heat stress. Through <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/gene-expression-profiling">transcriptome analysis</a> of the transgenic lines, we found significant up-regulation of various stress-responsive cowpea genes, having DRE in their promoter. Our results suggest that overexpression of VuDREB2A could improve cowpea production under drought and high temperatures.

World University root node

Department of Bioscience & Bioengineering

IIT Jodhpur

Plant Physiology and Biochemistry

Enhanced osmotic adjustment, antioxidant defense, and photosynthesis efficiency under drought and heat stress of transgenic cowpea overexpressing an engineered DREB transcription factor

Department of Metallurgical & Materials Engineering

International Journal of Fatigue

A Back-stress deconvolution method towards modelling of low cycle fatigue behavior of type 316L(N) stainless steel at room temperature

Recurrent spells of droughts are more common than a single drought, with intermittent moist recovery intervals. While the detrimental effects of the first drought on plant structure and physiology are unavoidable, if survived, plants can memorize the first drought to present a more robust response to the following droughts. This includes a partial stomatal opening in the watered recovery interval, higher levels of osmoprotectants and ABA, and attenuation of photosynthesis in the subsequent exposure. Short-term drought memory is regulated by ABA and other phytohormone signaling with transcriptional memory behavior in various genes. High levels of methylated histones are deposited at the drought-tolerance genes. During the recovery interval, the RNA polymerase is stalled to be activated by a pause-breaking factor in the subsequent drought. Drought leads to DNA demethylation near drought-response genes, with genetic control of the process. Progenies of the drought-exposed plants can better adapt to drought owing to the inheritance of particular methylation patterns. However, a prolonged watered recovery interval leads to loss of drought memory, mediated by certain demethylases and chromatin accessibility factors. Small RNAs act as critical regulators of drought memory by altering transcript levels of drought-responsive target genes. Further studies in the future will throw more light on the genetic control of drought memory and the interplay of genetic and epigenetic factors in its inheritance. Plants from extreme environments can give queues to understanding robust memory responses at the ecosystem level.

Planta

How do plants remember drought?

Department of Electrical Engineering

Department of Mathematics

Department of Computer Science & Engineering

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