SlGolS2 influences the metabolism of chlorophyll, carotenoid, and ethylene in tomato fruits

Galactinol synthase (GolS), which catalyzes the synthesis of galactinol, is the first critical enzyme in the biosynthesis of raffinose family oligosaccharides (RFOs) and contributes to plant growth and development, and resistance mechanisms. However, its role in fruit development remains largely unknown. In this study, we used CRISPR-Cas9 gene editing technology to create the slgols2 mutation showing uniformly green fruits without the dark green shoulder, and promoting fruit ripening. Further analysis revealed that the galactinol was undetected in slgols2 ovaries and fruits. Additionally, the mutant suppressed the accumulation of chlorophyll (Chl) and chloroplast development in tomato fruits. RNA sequencing analysis showed that genes related to chlorophyll accumulation and chloroplast development, such as SlPORB, SlGLK2, and SlCABs were downregulated in slgols2 fruits. Moreover, slgols2 lines prompted early color transformation and ethylene release by regulating the expression of genes such as SlPSY1, SlCRTISO, SlACS2, SlACS4, SlE4, SlE8, SlRIN, SlNOR and SlAP2a. Overall, our study provides evidence for the involvement of SlGolS2 in the pigment and ethylene metabolism of tomato fruits.