Transcription factor KUA1 positively regulates tomato resistance against Phytophthora infestans by fine-tuning reactive oxygen species accumulation.

Tomato is a horticultural crop of global significance. However, the pathogen Phytophthora infestans causing the late blight disease imposes a severe threat to tomato production and quality. Many transcription factors (TFs) are known to be involved in responses to plant pathogens, however, the key TFs in tomato resistant to P. infestans remain to be explored. Here, we identified six TFs related to tomato responses to P. infestans infection. In particular, we found overexpression of SlKUA1 could significantly improve tomato resistance to P. infestans; moreover, reactive oxygen species (ROS) accumulation was significantly increased in OE-SlKUA1 compared with WT after P. infestans infection along with higher expression of SlRBOHD. Surprisingly, we found that SlKUA1 could not bind to the promoter of SlRBOHD. Further experiments revealed that SlKUA1 inhibited the expression of SlPrx1 by binding to its promoter region, thereby decreasing POD enzyme abundance and causing compromised ROS scavenge. Meanwhile, we identified that SlKUA1 also binds to the promoter region of two plant immune-related genes, SlMAPK7 and SlRLP4, promoting their expression and enhancing tomato disease resistance. Together, our results have unraveled that SlKUA1 can boost tomato resistance against P. infestans through quantitatively regulating ROS accumulation and related immune gene expression, thus, providing promising new targets for breeding late blight resistance tomatoes.