Sugar metabolic and N-glycosylated profiles unveil the regulatory mechanism of tomato quality under salt stress

Tomato (Solanum lycopersicum L.) fruits undergo major metabolic changes in ripening stage. Many studies indicated that exogenous application of moderate salt during fruit ripening could improve tomato fruit quality. In addition, protein N-glycosylation played an important role in respond to salt stress and regulated fruit ripening. However, there is no reports about the link between N-glycosylation, salt stress and fruit quality. In this study, through GC–MS analysis, we measured the contents of 13 sugars metabolites and 10 sugars metabolites were significantly changed in salt treated tomato red rip fruits compared with the control red rip fruits. Then, using N-glycoproteome analysis, we identified 442 N-glycosites from 310 N-glycoproteins in comparison of salt-treated red ripe fruits and the control red ripe fruits. Interestingly, salt treatment dramatically triggered the down-regulation of N-glycosites, suggesting protein N-glycosylation reprogramming under salt condition. Following statistical analysis, the N-glycosylation levels of many proteins related to sugar conversion, taste-modifying and fruit firmness were significantly changed under salt treatment. Collectively, the data provides the link between N-glycosylation, salt stress and fruit quality for the first time. In addition, this study also contributed to understanding the effect of environmental changes on post-translational modification mediated fruit quality.