Silencing of the SlNAP7 gene influences plastid development and lycopene accumulation in tomato.

Ripening is an important stage of fruit development. To screen the genes associated with pigment formation in tomato fruit, a suppression subtractive hybridization (SSH) cDNA library was constructed by using tomato fruit in the green ripe and break ripe stages, and 129 differential genes were obtained. Using redness as a screening marker, virus-induced gene silencing (VIGS) of the differential genes was performed with a sprout vacuum-infiltration system (SVI). The results showed that silencing the SlNAP7 gene affected the chloroplast development of tomato leaves, manifesting as a photo-bleaching phenotype, and silenced fruit significantly affected the accumulation of lycopene, manifested as a yellow phenotype. In our study, we found that silencing the SlNAP7 gene downregulates the expression of the POR and PORA genes and destroys the normal development of the chloroplast. The expression of related genes included in the lycopene biosynthesis pathway was not significantly changed, but lycopene accumulation was significantly reduced in tomato fruit. Perhaps it was caused by the destruction of the chromoplast, which leads to the oxidation of lycopene. The results show that the SlNAP7 gene influences chloroplast development and lycopene accumulation in tomato.