MPK3/MPK6-mediated ERF72 Phosphorylation Positively Regulates Resistance to Botrytis cinerea Through Directly and Indirectly Activating the Transcription of Camalexin-biosynthesis Enzymes.

Ethylene response factor (ERF) Group VII members generally function in regulating plant growth and development, abiotic stress response, and plant immunity in Arabidopsis. However, the detail regulatory mechanism by which Group VII ERFs mediate plant immune responses remains elusive. Here, we characterised ERF72, a member of the Group VII ERFs, as a positive regulator mediating resistance to the necrotrophic pathogen Botrytis cinerea. Compared with wild type (WT), erf72 mutant showed the lower camalexin contents and more susceptible to B. cinerea, while complementation of ERF72 in erf72 rescued susceptibility phenotypes. Moreover, overexpression of ERF72 in WT promoted camalexin biosynthesis and resistance to B. cinerea. Then, we identified camalexin biosynthesis genes PAD3 and CYP71A13, and transcription factor WRKY33 as target genes of ERF72. Furthermore, MPK3 and MPK6 phosphorylate ERF72 at Ser151 to improve its transactivation activity, camalexin contents and resistance to B. cinerea. These findings highlight the role of ERF72 in coordinating the camalexin biosynthesis via directly regulating the expression of camalexin biosynthetic genes and indirectly by targeting WRKK33 in plant immunity.