CaWRKY20 Negatively Regulates Plant Resistance to Colletotrichum scovillei in Pepper.

ABSTRACT Chili anthracnose, a fungal disease caused by <italic>Colletotrichum scovillei</italic>, is among the most devastating diseases affecting pepper (<italic>Capsicum annuum</italic> L.). Although WRKY transcription factors play important roles in plant immunity, it is unknown how WRKY gene family members contribute to pepper plant resistance to <italic>C. scovillei</italic>. Here, <italic>CaWRKY20</italic> was found to negatively regulate pepper resistance to <italic>C. scovillei</italic>, which was demonstrated by virus‐induced gene silencing and transient overexpression in pepper. Moreover, overexpression of <italic>CaWRKY20</italic> enhanced susceptibility to <italic>C. scovillei</italic> in tomato. Additionally, our findings demonstrated that <italic>CaWRKY20</italic> can indirectly regulate the expression of salicylic acid (SA)‐related defense genes (<italic>CaPR1</italic>, <italic>CaPR10</italic> and <italic>CaSAR8.2</italic>) as well as reactive oxygen species (ROS)‐scavenging enzyme genes (<italic>CaCAT</italic>, <italic>CaPOD</italic> and <italic>CaSOD</italic>) in response to <italic>C. scovillei</italic>. In addition, CaWRKY20 was found to interact with CaMIEL1 in the nucleus to regulate the defense response to <italic>C. scovillei</italic> in pepper. Furthermore, CaWRKY20 directly bound to the W‐box in the promoter of <italic>SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1</italic> (<italic>CaSARD1</italic>) and suppressed its expression, resulting in reduced resistance to <italic>C. scovillei</italic>. These results will clarify the mechanism by which WRKY transcription factors are involved in pepper disease resistance and can thus facilitate molecular breeding for anthracnose‐resistant varieties. [ABSTRACT FROM AUTHOR]