Overexpression of an Antioxidant Enzyme APX1 in Mutant Restores its Pleiotropic Growth Phenotype.

Breeding crops with enhanced immunity is an effective strategy to reduce yield loss caused by pathogens. The () mutant shows enhanced pathogen resistance but retarded growth; thus, it restricts the application of in breeding crops with disease resistance. Reactive oxygen species (ROS) play important roles in plant growth and defense. In this study, we determined that the mutant exhibited excessive ROS accumulation. However, the mutation of respiratory burst oxidase homolog D (RBOHD), a reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase responsible for the production of ROS signaling in plant immunity, did not suppress excessive ROS levels in . Furthermore, the mutant showed low levels of ascorbate peroxidase 1 (APX1), an important cytosolic ROS-scavenging enzyme. overexpression in the background removed excessive ROS and restored the pleiotropic growth phenotype. Notably, overexpression did not reduce the resistance of mutant to virulent strain pv. () DC3000 and avirulent strain DC3000 (). These results suggest that the removal of excessive ROS by overexpression restored the growth phenotype while conserving pathogen resistance. Hence, our study provides a theoretical and empirical basis for utilizing CPR5 in the breeding of crops with disease resistance by effective oxidative stress management via APX1 expression.