Abstract: A field experiment was conducted to investigate the effects of straw returning on activities and gene expression of key enzymes related to tuber starch synthesis in rainfed potato (Qingshu 9) during tuber formation. We measured the activities and gene expression of key enzymes related to starch synthesis, starch gelatinization characteristics, and starch accumulation. Theresults showed that straw returning significantly enhanced activity of SSS enzyme, gene expression of SSII and SSIII, starch breakdown, amylase content and ratio of amylase to amylopectin, and decreased activities of AGPP and GBSS enzyme, gene expression of AGPase, GBSSI, SBEI, and SBEII, starch viscosity at various stages, starch retrogradation, and total starch content, but not affected SBE enzyme activity and starch pasting temperature in the whole process of tuber formation. GBSS enzyme activity was significanly positively correlated with AGPase, SBEIgene expression, and negatively correlated with amylase content and ratio of amylase to amylopectin. SBE enzyme activity was significantly positively correlated with SSIIgene expression, peak viscosity, trough viscosity, final viscosity and total starch content, and negatively correlated with starch breakdown and pasting temperature. AGPase gene expression was significantly negatively correlated with amylase content.GBSSIgene expression had a significantly positive correlation with starch final viscosity and starch retrogradation, and a significantly negative correlation with starch pasting temperature. Starch gelatinization was not significantly correlated with starch accumulation.

Key words:  , terrace, historical transformation, land abandonment., agriculture