Cloning and Expression Analysis of Tomato <i>SlSPS1</i> Gene

Sucrose is the main product of plant photosynthesis and participates in many physiological and biochemical reactions of plants. Sucrose phosphate synthase is one of the key rate-limiting enzymes necessary for sucrose to enter various metabolic pathways, and its activity directly reflects the ability of sucrose synthesis in plants. In order to study the mechanism of sucrose synthesis in tomato, this study cloned a sucrose phosphate synthase gene from tomato pulp and named it SlSPS1 . Through bioinformatics analysis, it was found that its cDNA is 3488bp in length, encoding 1054 amino acids, and there are 3 functional domain. There are 4 SPS genes in tomato, and their homology is relatively high. In Salicaceae crops, SlSPS1 protein is closely related to potatoes, peppers and eggplants. The results of tissue-specific analysis found that SlSPS1 was expressed in all tomato tissues, among which the expression was relatively high in the seedling stage and different development stages of the fruit. In order to further study the mechanism of SlSPS1 in tomato growth and sucrose accumulation, an overexpression and knockout vector of SlSPS1 was constructed and transformed into Micro-Tom to obtain transgenic positive lines. Analysis of the expression level of SlSPS1 on the obtained transgenic lines showed that the expression levels of the overexpression lines at the seedling stage, fruit green ripe stage and ripening stage were significantly up-regulated compared with the wild type, and the enzyme activity and sucrose content increased. Compared with the wild type, the expression of SlSPS1 at the seedling stage, green ripe stage and ripening stage of the knockout line was significantly down-regulated, and the enzyme activity and sucrose content were reduced. As for the mechanism of SlSPS1 in tomato growth and fruit sucrose accumulation, functional verification is needed in the future.