Recently, the innovative research team of the Crop Pathogen Functional Genomics Research Group at the Institute of Plant Protection, Chinese Academy of Agricultural Sciences, published a research paper in the sub-journal "Developmental Cell" of "Cell." The study reported a novel mechanism in rice broad-spectrum disease resistance regulation by the E3 ubiquitin ligase OsRING113-transcription factor APIP5 module through targeting serine protease inhibitors.
Rice is a globally important food crop, and diseases like rice blast and bacterial leaf blight pose serious threats to rice production. Uncovering broad-spectrum disease resistance genes in rice and deciphering their molecular mechanisms are crucial for breeding disease-resistant rice varieties and developing new disease control strategies.
In their previous research, the team found that the transcription factor APIP5 is a key downstream regulator of the disease resistance protein Piz-t. APIP5 mainly inhibits the expression of the phenylalanine metabolic gene cluster at the transcription level and enhances the mRNA degradation of small G protein genes at the post-transcriptional level to confer resistance against rice blast disease. However, the regulation of APIP5 protein stability was not clear.
This study revealed that the APIP5 protein is degraded by the 26S proteasome system. Researchers further screened the E3 ubiquitin ligase library (UbE3) created by the team and identified the E3 ubiquitin ligase OsRING113 as the target for APIP5. Ubiquitination analysis showed that OsRING113 promotes the degradation of APIP5 protein through K48 polyubiquitination. Overexpression of OsRING113 in rice enhanced broad-spectrum resistance against rice blast and bacterial leaf blight without affecting normal rice growth. RNA-seq analysis revealed similar transcriptional regulation patterns between OsRING113 overexpression and apip5 mutants. Further investigation found that the transcription factor APIP5 suppresses the expression of the Bowman-Birk serine protease inhibitor genes OsBBTI5 and APIP4. Genetic analysis indicated that OsBBTI5 and APIP4 positively regulate resistance against rice blast and bacterial leaf blight by enhancing the accumulation of the pathogenesis-related protein OsPR1aL, thus improving rice disease resistance.
This study unveils a hierarchical regulatory mechanism of plant broad-spectrum disease resistance mediated by the E3 ubiquitin ligase-transcription factor-serine protease inhibitor-pathogenesis-related protein, providing an important theoretical basis and candidate genes for breeding new varieties of disease-resistant crops.
Related Paper Information: https://doi.org/10.1016/j.devcel.2024.05.003
