PgMYB96 enhances <i>Physalis grisea</i> high temperature tolerance by activating trithorax-like factor WD REPEAT CONTAINING5b

Under the general trend of global warming, high temperature stress (HTS) is an increasingly serious challenge to the normal growth and development of crops. Exposure to high temperature (42 °C) during the growth and development stages of Physalis grisea can result in the breakdown of antimicrobials, sterility of pollen, and diminished yields. In this study, the trithorax-like factor gene PgWDR5b was functionally analysed in response to high temperature stress in P. grisea. PgWDR5b expression was enhanced through treatments with HTS and abscisic acid (ABA), PgWDR5b promoted the level of expression of downstream ABA synthesis genes after HTS, and positively contributes to tolerance to high temperature stress in P. grisea. In addition, the transcription factor PgMYB96 binds the promoter of PgWDR5b. Silencing both PgWDR5b and PgMYB96 reduced the high temperature tolerance of P. grisea. ABA synthesis genes showed decreased expression while the catabolic genes had increased levels of expression. In contrast, PgWDR5b and PgMYB96 overexpression plants incresed ABA content and more tolerance to high temperature stress. Furthermore, ABA directly activates PgWDR5b expression. These results collectively suggest that PgMYB96 can both regulate PgWDR5b expression by affecting ABA synthesis and directly activate PgWDR5b transcription. Hence, PgWDR5b can participate in the HTS response of P. grisea through the ABA metabolic pathway, and establishes a positive feedback regulatory mechanism with ABA.