Transcriptional response of otsA, P5CR, glgX, nodC, and molecular chaperone genes under the PEG-induced drought stress in Mesorhizobium ciceri Ca181

Abstract

Abstract This study was carried out to elucidate the mechanism of drought stress tolerance in bacterium Mesorhizobium ciceri Ca181, and further to correlate the finding with various salts impacts on the survival. Expression analysis of genes otsA, P5CR, glgX, major chaperone; groELS, dnaKJ, and nodulation protein-coding nodC genes were carried to reveal their roles in enhancing the PEG-induced drought tolerance. Yeast extract mannitol (YEM) broth supplemented with 47% polyethylene glycol (PEG-6000; w/v) was used to create the drought stress environment in the medium and strain Ca181 was able to tolerate PEG-induced drought stress for up to 5 days of incubation at 28 °C. PEG-induced desiccated cells showed variable expression patterns at the time interval of 5 min, 15 min, 1 h, 4 h, 8 h, 48 h, and 120 h. All the genes showed low levels of expression when the cells were grown until exponential growth phase in the presence of PEG-induced drought stress. However, when cells at the exponential phase of growth were incubated with PEG, maximum expression occurred after 5 min and 15 min, followed by a rapid decrease in the expression of otsA, P5CR, nodC, and molecular chaperone genes while the maximum expression of glgX was observed after 1 h of PEG-induced drought stress. The present study expands our information related to PEG-induced drought stress tolerance in strain Ca181, and impacts of salts additionally, expression analysis of these genes will contribute to our understanding of the molecular mechanism.