Reactive oxygen species and reactive nitrogen species induce lysigenous aerenchyma formation through programmed cell death in rice roots under submergence

Nitric oxide (NO) plays a significant role in plants under different abiotic stress. However, the influence of NO and other reactive nitrogen species (RNS) in employing nitrosative stress in rice seedlings under submergence remains unexplored. Submergence also stimulates the development of lysigenous aerenchyma, facilitating oxygen supply to roots but the contribution of NO and RNS in aerenchyma formation under submergence is not known. Present study investigated the major components of the nitro-oxidative stress and their association with lysigenous aerenchyma development in the Sub1 near isogenic line of rice under submergence. Following submergence, Swarna showed increased NADPH oxidase (NOX) activity with excess reactive oxygen species (ROS) production in roots. Submergence also caused increased NO content and membrane lipid peroxidation in Swarna roots. Submergence-induced ROS and RNS accumulation in roots disturbed the redox homeostasis leading to the formation of lysigenous aerenchyma through programmed cell death (PCD). PCD was also accompanied by altered cytoplasmic streaming and DNA damage. In the present study Swarna Sub1 exhibited increased SOD, CAT, POX, APX, GR and GSNOR activity with subsequent detoxification of ROS and RNS; eventually decreasing the aerenchyma formation in root under submerged conditions. Overall, the study established ROS and RNS-mediated unique mechanism in lysigenous aerenchyma formation in rice roots under submergence.