A D-cysteine desulfhydrase, SlDCD2, participates in tomato fruit ripening by modulating ROS homoeostasis and ethylene biosynthesis.

Hydrogen sulfide (HS) is involved in multiple processes during plant growth and development. D-cysteine desulfhydrase (DCD) can produce HS with D-cysteine as the substrate; however, the potential developmental roles of DCD have not been explored during the tomato lifecycle. In the present study, showed increasing expression during fruit ripening. Compared with the control fruits, the silencing of by pTRV2- accelerated fruit ripening. A gene-edited mutant was constructed by CRISPR/Cas9 transformation, and the mutant exhibited accelerated fruit ripening, decreased HS release, higher total cysteine and ethylene contents, enhanced chlorophyll degradation and increased carotenoid accumulation. Additionally, the expression of multiple ripening-related genes, including , , , , , , , and was enhanced during the mutant tomato fruit ripening. Compared with the wild-type fruits, mutation induced HO and malondialdehyde (MDA) accumulation in fruits, which led to an imbalance in reactive oxygen species (ROS) metabolism. A correlation analysis indicated that HO content was strongly positively correlated with carotenoids content, ethylene content and ripening-related gene expression and negatively correlated with the chlorophyll content. Additionally, the mutant showed earlier leaf senescence, which may be due to disturbed ROS homeostasis. In short, our findings show that is involved in HS generation and that the reduction in endogenous HS production in the mutant causes accelerated fruit ripening and premature leaf senescence. Additionally, decreased HS in the mutant causes excessive HO accumulation and increased ethylene release, suggesting a role of HS and in modulating ROS homeostasis and ethylene biosynthesis.