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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]

Rice blast and bacterial blight, caused by the fungus Magnaporthe oryzae and the bacterium Xanthomonas oryzae pv. oryzae (Xoo), respectively, are devastating diseases affecting rice. Here, we report that a rice valine-glutamine (VQ) motif-containing protein, OsVQ25, balances broad-spectrum disease resistance and plant growth by interacting with a U-Box E3 ligase, OsPUB73, and a transcription factor, OsWRKY53. We show that OsPUB73 positively regulates rice resistance against M. oryzae and Xoo by interacting with and promoting OsVQ25 degradation via the 26S proteasome pathway. Knockout mutants of OsVQ25 exhibit enhanced resistance to both pathogens without a growth penalty. Furthermore, OsVQ25 interacts with and suppresses the transcriptional activity of OsWRKY53, a positive regulator of plant immunity. OsWRKY53 downstream defense-related genes and brassinosteroid signaling genes are upregulated in osvq25 mutants. Our findings reveal a ubiquitin E3 ligase-VQ protein-transcription factor module that fine-tunes plant immunity and growth at the transcriptional and posttranslational levels. [Display omitted] • The U-box E3 ligase OsPUB73 positively regulates broad-spectrum disease resistance • OsPUB73 interacts with and promotes the degradation of the VQ-motif protein OsVQ25 • The osvq25 mutant confers broad-spectrum disease resistance without a growth penalty • OsVQ25 interacts with and suppresses the transcriptional activity of OsWRKY53 Hao et al. show that loss-function of a VQ-motif-containing protein OsVQ25 confers broad-spectrum disease resistance. A U-box E3 ligase OsPUB73 interacts with and degrades OsVQ25, while OsVQ25 suppresses the transcriptional activity of a transcription factor OsWRKY53, highlighting that OsVQ25 balances plant immunity and growth by a hierarchical regulatory mechanism. [ABSTRACT FROM AUTHOR]