Changes in reactive oxygen scavenging systems and protein profiles in maize roots in response to nitric oxide under waterlogging stress

Abstract

Twenty days old pot grown seedlings of two genotypes of maize <em>viz.</em> HUZM-265 (waterlogging resistant) and HUZM-55 (waterlogging susceptible) were subjected to root zone waterlogging supplemented with 50, 500 and 2000 µmol/L sodium nitroprusside (SNP) as a donor of NO. Levels of reactive oxygen species (ROS) scavenging enzymes and non-enzymes were quantified in terminal root portions at 9, 12, 15, 18 and 21 h after waterlogging. In waterlogged plants, there was a significant increase in the levels of catalase (CAT), peroxidase (POX), superoxide dismutase (SOD), ascorbate peroxidase (APX) and alcohol dehydrogenase (ADH) and the increment was more in the resistant genotype. Levels of non-enzymatic antioxidants <em>viz.</em> ascorbic acid and phenols decreased, but to a lesser magnitude in the resistant genotype. After waterlogging, there was a differential pattern in variation in the levels of studied enzymes and non-enzymes with time. It is observed that ADH, CAT, and APX play a significant role to scavenge ROS at an early stage, while POX and SOD at later stages of waterlogging stress. In normal and waterlogged plants of HUZM-265, a low molecular weight protein of 20 kDa was visible, and at 500 and 2000 μmol/L SNP treatments another protein of 43 kDa appeared in this genotype under the influence of SNP. No such proteins were evident in HUZM-55. NO influenced studied parameters, but response varied with respect to genotypes, dose, and duration of waterlogging.