Identification of Eggplant SmMPK Gene Family and Functional Verification of SmMPK4.1

Light is one of the important factors influencing anthocyanin synthesis, and low-light conditions (<2000 Lux) seriously affect the coloration of the peels of purple eggplant. MPK4 is an important protein kinase that regulates a number of physiological processes and is equivalent to the “molecular switch” in the plant. The function of MPK4 has been studied in Arabidopsis, rice, and apple, but its function in eggplant has not been reported. In this study, 16 SmMPK genes were identified using photo-sensitive eggplant ‘LSHX’ as a material. We found that overexpression of SmMPK4.1 could affect the phenotype of eggplant leaves and metabolites of fruits, and knockout of SmMPK4.1 affected the function of synthesizing anthocyanin in eggplant induced by high light (10,000 Lux). Furthermore, we demonstrated that SmMPK4.1 could interact with SmMYB75 in yeast and that SmMPK4.1 negatively regulated the function of anthocyanin synthesis by SmMYB75. The results of this study revealed the function of SmMPK4.1 and provided candidate genes for conducting high-quality breeding of eggplant in production.