Expression of the sweet potato peroxidase gene swpa4 in Arabidopsis activates defense genes mediated by reactive oxygen species and nitric oxide

Abstract

Previously transgenic tobacco plants over-expressing the sweet potato peroxidase gene swpa4 exhibited increased tolerance to various stress conditions. Expression of swpa4 in tobacco also has a positive effect on expression of genes related to reactive oxygen species (ROS) and nitric oxide (NO). Expression levels of respiratory burst oxidase protein D (RBOHD), a major gene regulating ROS, and nitric oxide associated 1 (NOA1), a gene involved in NO generation, are significantly affected by peroxidase inhibitor treatments. In this study, swpa4 was expressed in the rbohD and noa1 knock-out mutants of Arabidopsis, as well as in wild-type plants. The transgenic plants showed increased levels of ROS and NO. Expression of swpa4 activated expression of genes related to ROS and NO. This suggested that swpa4 regulated H2O2 and NO homeostasis, thereby establishing a potential molecular link between the defense signaling pathways mediated by ROS and NO.