Ectopic expression of BrALDH7B2 gene encoding an antiquitin from Brassica rapa confers tolerance to abiotic stresses and improves photosynthetic performance under salt stress in tobacco

Abstract

Improved plant performance under salt and drought stresses has been a challenging task to the plant due to the complexity and multitude of genes that govern them. We describe here, isolation and characterization of an aldehyde dehydrogenase gene (BrALDH7B2) that encodes an antiquitin isolated from Brassica rapa. Overexpression of the antiquitin gene in tobacco conferred tolerance to salt and drought stresses at the seedling stage as reflected by fresh weight, root length, and chlorophyll and carotenoid contents. The improved physiological characteristics observed in the transgenics may be ascribed to better PIabs, Pn, gs, WUE and E leading to better endurance under salt stress. The overexpression of BrALDH7B2 improved photosynthetic performance accompanied by reduced ROS formation followed by repressed cell-death in roots as determined by intracellular accumulation of H2DCF-DA and PI during salt stress in transgenic plants. Under salt stress, ALDH expressing tobacco transgenic plants showed activation of abiotic stress-responsive genes and vigorous ROS-scavenging system at the molecular level. Altogether, BrALDH7B2 represents a good candidate gene for orchestrating stress responses and with potential for engineering stress tolerance in different crops. To the best of our knowledge, this is the first report on functional study of BrALDH gene in the heterologous system tobacco with enhanced photosynthetic performance under salt stress.