The rice peroxisomal receptor PEX5 negatively regulates resistance to rice blast fungus Magnaporthe oryzae.

The receptor protein PEX5, an important component of peroxisomes, regulates growth, development, and immunity in yeast and mammals. PEX5 also influences growth and development in plants, but whether it participates in plant immunity has remained unclear. Here, we report that knockdown of OsPEX5 enhances resistance to the rice blast fungus Magnaporthe oryzae. We demonstrate that OsPEX5 interacts with the E3 ubiquitin ligase APIP6, a positive regulator of plant immunity. APIP6 ubiquitinates OsPEX5 in vitro and promotes its degradation in vivo via the 26S proteasome pathway. In addition, OsPEX5 interacts with the aldehyde dehydrogenase OsALDH2B1, which functions in growth-defense trade-offs in rice. OsPEX5 stabilizes OsALDH2B1 to enhance its repression of the defense-related gene OsAOS2. Our study thus uncovers a previously unrecognized hierarchical regulatory mechanism in which an E3 ubiquitin ligase targets a peroxisome receptor protein that negatively regulates immunity in rice by stabilizing an aldehyde dehydrogenase that suppresses defense gene expression. [Display omitted] • OsPEX5 negatively regulates immunity in rice • OsPEX5 interacts with and is ubiquitinated by APIP6 • APIP6 positively regulates the plant response to rice blast by degrading OsPEX5 • OsPEX5 stabilizes OsALDH2B1 to increase its inhibitory effect on OsAOS2 The peroxisomal receptor protein PEX5 is a crucial component of peroxisomes. You et al. show that OsPEX5, modulated by the E3 ubiquitin ligase APIP6, negatively regulates immunity in rice. In addition, OsPEX5 interacts with and stabilizes the aldehyde dehydrogenase OsALDH2B1 to inhibit the expression of the defense gene OsAOS2. [ABSTRACT FROM AUTHOR]