Relationship between Neutral Invertase Activity and Sugar Contents in Tomato Fruit and Its Functional Prediction Analysis

Abstract

Aims: Neutral invertase (NI) probably plays an important role in sucrose metabolism of tomato, but main function and mechanism are unclear. In this study, contents of soluble sugar and NI activity were measured at different stages in tomatoes of Solanum chmielewskii and Solanum lycopersicumc, meanwhile analyzed the correlation between contents of soluble sugar and NI activity, also cloned NI gene and predicted by bioinformatics for further making clear the function of NI in tomato sugar metabolism. Study Design: In order to analyze the function and action mechanism of NI, we used the tomato as materials, measured the contents of soluble sugars, activity of NI, and cloned the gene of NI. We also analyzed the NI with bioinformatics, and predicted the molecular function of NI for further making clear the function of NI in tomato sugar metabolism. Place and Duration of Study: College of Biological Science and Technology, between February 2016 and March 2017. Methodology: The contents of soluble sugar in tomato fruits were measured with HPLC (High performance liquid chromatography). The function structure and interacting proteins with NI family were predicted by bioinformatics. Results: The contents of glucose and fructose were significantly higher in Solanum lycopersicum than those in Solanum chmielewskii, and greatly increased along with the process of fruit mature period. Nevertheless, the content of sucrose was raised obviously in the mature period of wild type fruit. In normal cultivated tomato, NI activity was positively correlated with fructose and glucose contents, and negatively correlated with sucrose content. In order to further study the function of neutral invertase, the NI gene was cloned and analyzed by bioinformatics. The analysis results showed that the NI was glycosyl hydrolases with Glyco_hydro_100 conserved domain. Conclusion: The contents of glucose and fructose were significantly higher in Solanum lycopersicum than those in Solanum chmielewskii, and greatly increased along with the process of fruit mature period. The content of sucrose was raised obviously in the mature period of wild type fruit. NI activity in normal cultivated tomato was positively correlated with fructose and glucose contents, and negatively correlated with sucrose content. The NI was glycosyl hydrolases with Glyco_hydro_100 conserved domain, and might play an important role in the regulation of soluble sugar contents in tomato fruit.