The tomato histone deacetylase SlHDA1 contributes to the repression of fruit ripening and carotenoid accumulation

Histone deacetylation is one of the well characterized post-translational modifications related to transcriptional repression in eukaryotes. The process of histone deacetylation is achieved by histone deacetylases (HDACs). Over the last decade, substantial advances in our understanding of the mechanism of fruit ripening have been achieved, but the role of HDACs in this process has not been elucidated. In our study, an RNA interference (RNAi) expression vector targeting SlHDA1 was constructed and transformed into tomato plants. Shorter fruit ripening time and decreased storability were observed in SlHDA1 RNAi lines. The accumulation of carotenoid was increased through an alteration of the carotenoid pathway flux. Ethylene content, ethylene biosynthesis genes (ACS2, ACS4 and ACO1, ACO3) and ripening-associated genes (RIN, E4, E8, Cnr, TAGL1, PG, Pti4 and LOXB) were significantly up-regulated in SlHDA1 RNAi lines. In addition, the expression of fruit cell wall metabolism genes (HEX, MAN, TBG4, XTH5 and XYL) was enhanced compared with wild type. Furthermore, SlHDA1 RNAi seedlings displayed shorter hypocotyls and were more sensitive to ACC (1-aminocyclopropane-1-carboxylate) than the wild type. The results of our study indicate that SlHDA1 functions as a negative regulator of fruit ripening by affecting ethylene synthesis and carotenoid accumulation.