Tomato Synaptotagmin F accelerates fruit ripening, shortens fruit shelf-life and increases susceptibility to Penicillium expansum

Abstract

Synaptotagmins (SYTs), initially identified as calcium sensors for regulating synaptic vesicle exocytosis and endocytosis in mammalian neurons, play crucial role in biotic and abiotic stresses in plants. However, the function of SYTs in fruit ripening is unclear. In this study, a tomato Synaptotagmins gene, SlSYTF, was found to accelerate tomato fruit ripening. SlSYTF encodes an endoplasmic reticulum localized protein whose transcription is continuously enhanced during fruit ripening. Overexpression SlSYTF in tomato resulted in accelerated ripening progress, increased carotenoid content as well as decreased the firmness of tomato fruit, whereas the mutant slsytf-c exhibited the opposite phenotype. Importantly, SlSYTF could increase ethylene production by activating the expression of ethylene synthesis genes and prompt cell wall degradation by increasing pectinase and cellulase activities. Nevertheless, the accelerated cell wall degradation and thinned cuticle due to SlSYTF results in reduced shelf life and pathogen resistance. Collectively, we revealed a new SYTs gene that plays a dual role in tomato fruit ripening and pathogen response. This finding may shed new light on the relationship between maturation and immunity.