Overexpression of EcDREB2A transcription factor from finger millet in tobacco enhances tolerance to heat stress through ROS scavenging

• Published in: Journal of biotechnology 2021-08, Vol.336, p.10-24
• Main Authors: Singh, Sonam, Chopperla, Ramakrishna, Shingote, Prashant, Chhapekar, Sushil Satish, Deshmukh, Rupesh, Khan, Suphiya, Padaria, Jasdeep C., Sharma, Tilak Raj, Solanke, Amolkumar U.
• Format: Article
• Language: English
• Subjects: DREB2A; Droughts; Eleusine - genetics; Eleusine - metabolism; Enzyme activity; Finger millet; Gene Expression Regulation, Plant; Heat stress; Heat-Shock Response - genetics; Nicotiana - genetics; Nicotiana - metabolism; Plant Proteins - genetics; Plant Proteins - metabolism; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; Reactive Oxygen Species - metabolism; ROS scavenging; SSH library; Stress, Physiological - genetics; Transcription factor; Transcription Factors - genetics; Transcription Factors - metabolism
• ISSN: 0168-1656; 1873-4863
• DOI: 10.1016/j.jbiotec.2021.06.013

•EcDREB2A, a novel A-2 type DREB gene highly expressed in different abiotic stress particularly heat stress.•EcDREB2A shows significantly high expression in various developmental stages of finger millet.•EcDREB2A transgenic plants showed enhanced heat tolerance by regulating the ROS homeostatis and upregulation of the stress-responsive genes.•EcDREB2A gene involved in scavenging excess ROS in heat stress response by regulating the enzyme activity of SOD, CAT, GR, POD and APX proteins. An extreme temperature regime beyond desired level imposes significant stress in crop plants. The low and high temperature stresses are one of the primary constraints for plant development and yield. Finger millet, being a climate resilient crop, is a potential source of novel stress tolerant genes. In this study, functional characterization of finger millet DREB2A gene in different abiotic stress conditions was done. This novel EcDREB2A transcription factor isolated from finger millet is a truncated version of DREB2A gene compared to previously reported DREB genes from other plant species. The overexpression of EcDREB2A in transgenic tobacco exhibits improved tolerance against heat stress 42 °C for up to 7 days, by altering physiology and biochemical means. However, same transgenic lines were unable to provide tolerance to 200 mM NaCl and 200 mM Mannitol stress. Under heat stress conditions, increased seed germination with improved lateral roots, fresh and dry weight relative to wild type (WT) was observed. The EcDREB2A transgenics exposed to heat stress showed improved rate of stomatal conductance, chlorophyll and carotenoids contents, and other photosynthesis parameters compared to WT plants. EcDREB2A overexpression also resulted in increased antioxidant enzyme activity (SOD, CAT, GR, POD and, APX) with decreased electrolyte leakage (EL), H2O2, and malondialdehyde (MDA) content than WT plants under heat stress. Quantitative real time expression analysis demonstrated that all eight downstream genes were significantly upregulated in transgenic plants only after heat stress. Our data provide a clear demonstration of the positive impact of overexpression of EcDREB2A providing heat stress tolerance to plants.