Effects of salinity on sucrose metabolism during tomato fruit development
The objective of this study was to investigate the effects of salt stress on content of carbohydrate and activity of sucrose-metabolizing enzyme and gene expression patterns and to provide a new evidence for tolerating salt stress of cultivated tomato. The related enzymes’ activities of sucrose metabolism including invertase, sucrose synthase and sucrose phosphate synthase and the expression of acid invertase and sucrose synthase mRNAs were determined. The results indicated that hexoses (fructose and glucose) accumulated to higher levels and the content of sucrose and starch is lower in mature fruit under salt stress treatments; the salinity can maintain or enhance the invertase activities of tomato fruit in a long period of time (20 - 60 days after anthesis) and elevate the expression of acid invertase mRNA. Salinity could also regulate the sucrose synthase activity by controlling its gene expression. But the effects of salinity treatment on sucrose phosphate synthase activities were weak under the condition of salt stress. It showed that salinity could regulate the activity of sucrosemetabolizing enzymes by controlling its gene expression under salt stress.