Identification and knockout of SlHDZIV14 reveals fruit trichome-associated control of postharvest water loss in tomato

Abstract

Fruit water loss critically affects shelf life and is closely related to the density of trichomes on the fruit surface. Despite this relationship, the functions of fruit trichomes and the molecular mechanisms underlying their formation in tomato remained largely unknown. In this study, we identified the HD-ZIP IV transcription factor SlHDZIV14 as a key regulator of fruit trichome formation, demonstrated by the glabrous fruit surface of its knockout mutant. Importantly, the reduced abundance of fruit trichomes significantly lowered the postharvest water loss rate, emphasizing the importance of fruit trichomes in regulating postharvest dehydration. Furthermore, our findings demonstrated that SlCycB2 physically interacted with SlHDZIV14, which, in turn, represses the expression of both SlCycB2 and SlWRKY75. We also demonstrated that these genes were participated in the formation of fruit trichomes on tomato and thereby influence the fruit postharvest water loss. Additionally, we found that SlHDZIV14 was inducible by methyl jasmonate (MeJA) and interacted with SlJAZ1/2/7 proteins, which further suppresses its transcriptional activity on trichome-related genes. Our study revealed the critical role of fruit trichomes in postharvest water regulation and provided new insights into potential targets for improving tomato shelf life through breeding or biotechnological approaches.