A transcription factor SlWRKY71 activated the HS generating enzyme SlDCD1 enhancing the response to Pseudomonas syringae pv DC3000 in tomato leaves.

HS is a well-known gaseous signaling molecule that plays important roles in plant response to biotic stresses. Pseudomonas syringae pv tomato (Pst) could cause enormous loss, while whether HS could modulate plant defense against Pst is still unclear. By CRISPR/Cas9, the Sldcd1 gene editing mutant showed reduced endogenous HS content and attenuated resistance, whereas treatment with exogenous HS could enhance the resistance. A transcription factor, SlWRKY71, was screened and identified to promote the transcription of SlDCD1 via yeast one-hybrid, dual-luciferase reporter system, electrophoretic mobility shift assays, and transient overexpression. Here, it was found that exogenous HS relieved the symptoms of bacterial speck disease in tomato leaves, conferring tolerance to Pst. DC3000, and the expression of the HS-producing enzyme SlDCD1 was significantly induced. The Slwrky71 mutant also showed reduced defense in tomato leaves against Pst. DC3000, whereas SlWRKY71-OE tomato leaves showed increased tolerance. Transient overexpression of SlDCD1 in the context of Slwrky71 with exogenous HS treatment has stronger resistance, and the overexpression of SlWRKY71 in the context of Sldcd1 showed relatively weak disease resistance, and with the addition of HS enhanced the effect. Therefore, we concluded that SlWRKY71 could activate SlDCD1 expression and promote endogenous HS production, thereby improving tomato leaves resistance to Pst. DC3000.