Jasmonic Acid-Repressed MeTPL7 Negatively Modulates Disease Resistance through PHA Domain and Reactive Oxygen Species Accumulation

Cassava production is severely affected by cassava bacterial blight (CBB). TPL/TPR as an important transcriptional cofactor is involved in the plant immune process, whereas its relationship with cassava disease resistance is still unclear. In this study, 10 members of the MeTPL family were identified, and functional analysis revealed the negative modulation by MeTPL7 on disease resistance to CBB through reducing reactive oxygen species (ROS) burst. MeTPL7 significantly reduced the transcription of the MeRboh family especially MeRbohD, and overexpression of MeRbohD restored MeTPL7-mediated disease susceptibility. Notably, MeTPL7 contained a special PHA domain, whose deletion affected its specific nucleus localization, which was accompanied by decreased sensitivity in MeTPL7-overexpressed plants. In addition, jasmonic acid (JA) inhibited the transcription of MeTPL7, and overexpressing MeTPL7 alleviated JA-improved disease resistance. In summary, this study reveals that JA-repressed MeTPL7 negatively modulates disease resistance to CBB through ROS accumulation, providing a reference gene for genetic improvement in defense.