The MADS‐box protein SlTAGL1 regulates a ripening‐associated SlDQD/SDH2 involved in flavonoid biosynthesis and resistance against Botrytis cinerea in post‐harvest tomato fruit

Abstract

SUMMARY3‐Dehydroquinate dehydratase/shikimate dehydrogenase (DQD/SDH) is a key rate‐limiting enzyme that catalyzes the synthesis of the shikimate, which is an important metabolic intermediate in plants and animals. However, the function of SlDQD/SDH family genes in tomato (Solanum lycopersicum) fruit metabolites is still unknown. In the present study, we identified a ripening‐associated SlDQD/SDH member, SlDQD/SDH2, that plays a key role in shikimate and flavonoid metabolism. Overexpression of this gene resulted in an increased content of shikimate and flavonoids, while knockout of this gene by CRISPR/Cas9 mediated gene editing led to a significantly lower content of shikimate and flavonoids by downregulation of flavonoid biosynthesis‐related genes. Moreover, we showed that SlDQD/SDH2 confers resistance against Botrytis cinerea attack in post‐harvest tomato fruit. Dual‐luciferase reporter and EMSA assays indicated that SlDQD/SDH2 is a direct target of the key ripening regulator SlTAGL1. In general, this study provided a new insight into the biosynthesis of flavonoid and B. cinerea resistance in fruit tomatoes.