BcVQ11A‐BcWRKY23‐BcWRKY25 Module Is Involved in Thermotolerance by Regulating Phenylalanine Ammonia‐Lyase Activity in Non‐Heading Chinese Cabbage

Abstract

High temperature can significantly affect the quality and yield of plants. However, there has been limited research investigating the thermotolerance of non‐heading Chinese cabbage (NHCC). This study, identified BcWRKY23 through transcriptome analysis in NHCC with varying levels of thermotolerance. Overexpression and silencing experiments demonstrated that BcWRKY23 positively regulates the thermotolerance of NHCC by activating its own expression under short‐term heat stress (HS). Additionally, BcWRKY23 was found to bind to the promoter of BcWRKY25 and activate its expression, which also enhanced thermotolerance. BcWRKY23 and BcWRKY25 enhanced the expression of HSR genes to improve thermotolerance. Furthermore, BcPAL1 was shown to be activated by BcWRKY23, while BcPAL2 was activated by both BcWRKY23 and BcWRKY25. Overexpression of BcPAL1 and BcPAL2 in NHCC significantly increased thermotolerance, accompanied by an enhancement of phenylalanine ammonia‐lyase (PAL) activity. Moreover, under long‐term HS, the significant accumulation of BcVQ11A was observed, and the interaction between BcVQ11A and BcWRKY23 as well as BcWRKY25 inhibited the activation of them to target genes, resulting in decreased PAL activity. This study proposes a HS response pathway involving BcVQ11A‐BcWRKY23‐BcWRKY25‐BcPAL1/BcPAL2, providing valuable insights into the molecular mechanisms underlying thermotolerance in plants.