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.

Recent Advances in Mechanisms Underlying Defense Responses of Horticultural Crops to Botrytis cinerea

“…In addition to the reported major proteins, other proteins also play a role in the resistance of B. cinerea. Tomato SlDQD/SDH2 plays a key role in flavonoid biosynthesis and fruit resistance to B. cinerea [119]. Strawberry MANNOSE-BINDING LECTIN 1 (MBL1) is a member of the G-type lectin family and was involved in plant defense against B. cinerea [120].…”

Recent Advances in Studying the Regulation of Fruit Ripening in Tomato Using Genetic Engineering Approaches

“…Tomato fruit is rich in primary metabolites like sucrose [9][10][11][12], hexoses [13][14][15], organic acids [16][17][18][19][20][21][22][23], and amino acids [24]. Tomato fruit also contains various secondary metabolites, including pigments, mostly lycopene [25][26][27] and beta-carotene [28,29], and antioxidants, namely flavonoids [30][31][32][33][34], and ascorbic acid [35][36][37][38].…”