Plant growth regulator induced mitigation of oxidative burst helps in the management of drought stress in rice (Oryza sativa L.)

Drought is a major yield-limiting factor for rice production. Present study is a first of its own kind to show the promising role of plant growth regulators (PGRs) [methyl jasmonate (MJ), salicylic acid (SA), paclobutrazol (PBZ)] to mitigate drought induced notable variations in physio-biochemical parameters-relative water content (RWC), total antioxidant activity (TAO), total phenolic content (TPC), lipid peroxidation (LP), protein oxidation (PO), abscisic acid content (ABA) and NADPH oxidase (Nox) activity in contrasting rice genotypes-Nagina-22 (N-22, drought-tolerant) and Pusa Sugandh-5 (PS-5, drought-sensitive). It also revealed the changes in expressions of drought responsive genes (RD1, RD2) of AP2/ERF family and Nox family (Nox1, Nox5). A progressive increase in TPC (21–50 %), ABA content, (17–45 %), Nox (6–40 %), TAO (12–25 %) activity, while decrease in RWC (90−55 %), LP (64−25 %), PO (25−9 %) level, and expressions of RD1 and RD2 genes were found upregulated (∼1.4−1.8 fold) in primed samples under drought stress. Cloning, sequencing and characterization of Nox1 gene (accession number- MT771724) revealed its role in regulating oxidative burst during drought stress. Overall, seed-priming with MJ was identified to be highly effective to mitigate the deleterious effects of drought stress which could be further used to enhance drought tolerance in rice for improved yield under dry-land and rain-fed conditions.