| To explore the response mechanism of potato tuber starch synthesis to soil water stress, three water stress treatments of normal water supply (maintaining 75% of soil field water holdings), moderate water stress (maintaining 50% soil field holdings) and severe water stress (maintaining 25% of soil water content) were set up by pot experiments using potato varieties ‘Green Potato No. 9’ and ‘Min Potato No. 1’. The effect of soil water stress on expression of key enzyme genes and enzyme activity in potato tuber starch synthesis was studied by 50% of water stress and severe water stress (maintaining 25% of soil water content). The results showed that during tuber formation, soil water stress significantly improved the expression of AGPase, GBSSI, SBEI, SBEII, SSII and SSIII genes in potato tubers, and the degree of soil moisture stress, the SBEI, SBEII and SSII gene expression were upregulated. Soil water stress significantly reduced AGPase, GBSS, SBE, SSS activities in potato tubers, among which GBSS and SBE enzyme activity were down regulated. However, AGPase, GBSSI, SSIII gene expression and AGPase and SSS activity showed an opposite upward and downward trend between potato varieties ‘Green Potato No.9’ and ‘Min Potato No.1’. |