CmPIF8‐CmERF27‐CmACS10‐mediated ethylene biosynthesis modulates red light‐induced powdery mildew resistance in oriental melon.

Powdery mildew is a serious fungal disease in protected melon cultivation that affects the growth, development and production of melon plants. Previous studies have shown that red light can improve oriental melon seedlings resistance to powdery mildew. Here, after inoculation with Podosphaera xanthii, an obligate fungal pathogen eliciting powdery mildew, we found that red light pretreatment increased ethylene production and this improved the resistance of melon seedlings to powdery mildew, and the ethylene biosynthesis gene CmACS10 played an important role in this process. By analysing the CmACS10 promoter, screening yeast one‐hybrid library, it was found that CmERF27 positively regulated the expression of CmACS10, increased powdery mildew resistance and interacted with PHYTOCHROME INTERACTING FACTOR8 (CmPIF8) at the protein level to participate in the regulation of ethylene biosynthesis to respond to the red light‐induced resistance to P. xanthii, Furthermore, CmPIF8 also directly targeted the promoter of CmACS10, negatively participated in this process. In summary, this study revealed the specific mechanism by which the CmPIF8‐CmERF27‐CmACS10 module regulates red light‐induced ethylene biosynthesis to resist P. xanthii infection, elucidate the interaction between light and plant hormones under biological stress, provide a reference and genetic resources for breeding of disease‐resistant melon plants. Summary Statement: We found that ethylene was induced by red light and plays a positive role in the resistance of melon to powdery mildew. CmERF27 and CmPIF8 activate and inhibit the transcription of CmACS10, respectively, and regulate ethylene biosynthesis. Moreover, CmERF27 and CmPIF8 proteins interact, and this interaction interferes with the transcriptional activation of CmACS10 by CmERF27. [ABSTRACT FROM AUTHOR]