Temperature induced changes in anti-oxidative stress metabolism in maize

Abstract

Anti-oxidative system in plants comprising of enzymatic and non-enzymatic antioxidants imparts stress tolerance by scavenging/detoxification of excess reactive oxygen species (ROS) produced under high temperature stress. Present investigation deals with the estimation of metabolites and anti-oxidative enzyme activities in four inbred maize lines; NSJ221, NSJ189, PSRJ13099 and RJR270 in response to high temperature stress imposed at reproductive stage by staggered sowing. An increase in H2O2 and malondialdehyde (MDA) was observed in all the genotypes, however the increase was higher in PSRJ13099 and RJR270. The activities of studied enzymes increased in NSJ189 and NSJ221 while a decrease was observed in PSRJ13099 and RJR270. Under heat stress isoforms of SOD increased in NSJ189 and NSJ221 while a concomitant decrease was observed in PSRJ13099 and RJR270. Two new SOD-isoforms were also observed in NSJ221. GPX showed more number of high mobility isoforms with low activity in NSJ221 and less mobile isoforms with higher activity in both NSJ189 and NSJ221. Whereas, PSRJ13099 and RJR270 showed decrease band intensity of less mobile GPX-isoforms under heat stress. Activity of CAT-isoforms increased to a similar extent across the genotypes under heat stress. In case of non-enzymatic antioxidants, non-protein thiols increased in all the genotypes while the level of carotenoids depleted in all the genotypes except NSJ221. Ascorbate (AsA) levels depleted in PSRJ13099 and RJR270 and increased in NSJ189 and NSJ221 under heat stress. Understanding the intricate regulatory pathways in crop plants under heat stress will help in developing genotypes with enhanced stress tolerance.