Variations in ethylene sensitivity among mungbean [Vigna radiata (L.) Wilczek] genotypes exposed to drought and waterlogging stresses

Authors: SUSHEEL KUMAR RAINA, NIKHIL RASKAR, LALITKUMAR AHER, AJAY KUMAR SINGH, DHAMMAPRAKASH PANDHARI WANKHEDE, JAGADISH RANE, PARAMJIT SINGH MINHAS

Abstract: Ethylene is an important phytohormone that regulates several aspects of plant development including those crucial for drought tolerance. The main aim of the present work was to investigate variability in ethylene sensitivity of mungbeans to seed germination, waterlogging, and leaf senescence, and the underlying transcriptional regulation of ethylene biosynthetic/responsive genes. Significant variation was observed for silver-nitrate-mediated germination inhibition and flooding stress tolerance among the mungbean genotypes. Genotypes with differential ethylene sensitivity (IC-325817 and IC-325756) revealed variable leaf senescence rates upon exposure to exogenously supplied ethephon. Drought induced significant upregulation of VrACS7 and VrERF genes in the more sensitive genotype, implicating the role of plant moisture status in influencing ethylene biosynthesis/perception. Drought-mediated upregulation of VrACS7 transcripts was accompanied by reduced lateral root formation in the more sensitive genotype (IC-325756), although the same did not follow in the less sensitive genotype (IC-325817), which had reduced ethylene responsiveness. These studies emphasize the variability in ethylene sensitivity of mungbeans and reveal a genotype- dependent transcriptional regulation of ethylene biosynthetic/responsive genes upon drought in this waterlogging-sensitive legume crop.

Keywords: Mungbean genotypes, germination, chlorophyll fluorescence, ethephon, gene expression

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