The Research Of Relationship Between The Expressional Rules Of Sucrose Synthase Gene And The Sugar Content

Sorghum originated in Africa, and is a multipurpose plant, especially in poorenvironmental conditions. It can provide food, feed, fiber and fuel in a series of agriculturalecological system. Sweet sorghum is a variant of ordinary sorghum. It has rich and juicystalks of sugar content, also is the most promising energy material because it has higher sugarcontent, biological yield and higher ethanol conversion rate and the cost is relatively lowercompared with other crops. It has a strong production capacity in the bad condition. No matterhow to use sweet sorghum, it is a base to improve its stem sugar content. So, studying thepattern of sugar accumulation of sweet sorghum in different growth period, the expressionalrules of sucrose synthase, and its impact to the sugar content can laid a theoretical foundationto breed high sugar sweet sorghum varieties by biotechnology. It has important significance tothe improvement, development and effective use of sweet sorghum. This experiment studiesthe relationship between sugar content and the expressional rules of SS gene in differentgrowth period in sweet sorghum’s leaf and stem, including W452、Roma and commonsorghum Xinliang52. And verify the accuracy of experimental results, the repeatability byrepeating experimental data for two years. The conclusions are as follows:1. In the leaf and stem of sorghum, total sugar content is approximately equal to the numberthat sucrose content adds reducing sugar content. And reducing sugar content isapproximately equal to the contents of glucose adds fructose content. In the maximum periodof total sugar accumulation in sweet sorghum and ordinary sorghum, the sugar content ofsweet sorghum is3times more than ordinary sorghum and sucrose content is4times morethan ordinary sorghum. And reducing sugar content is no big difference. The study shows thatsucrose content is the main factor to influence the total sugar content.2. Conducting the correlation analysis of the total sugar content and sucrose, fructose, glucosecontent respectively in stem of sorghum and sweet sorghum and the results show that it isvery significant positive correlation between total sugar and sucrose(R=0.972，P<0.01). Andthe change trend of glucose, fructose content and total sugar is different. The content offructose has negatively correlated with total sugar content(R=-0.6，P=0.045<0.05). Thecontent of glucose has not associated with total sugar in sweet sorghum(R=0.309，P=0.142).In common sorghum, total sugar and sucrose is significantly positive correlation(R=0.629，P<0.01). The content of fructose has negatively correlated with total sugar(R=-0.725，P<0.05). And the content of glucose has not associated with total sugar(R=O.425，P=0.129), whichshows that sucrose is the main accumulation in sorghum stem and total sugar content changeswith the change of sucrose content. This is the key factor causing the different sugar betweensweet sorghum and common sorghum.3. The quantitative analysis of SS gene shows that with the growth of sorghum, the expressionof SS gene is consistent in leaf and stem while its expression in sweet sorghum is inconsistentwith common sorghum. The changing trend of the expression of SS gene is consistent withsucrose content change in sweet sorghum leaf and stem. It is related with the role of synthesisand decomposition of SS gene, which is the leading factor of different sucrose accumulation.In the sweet sorghum, the expression rules of SS gene is consistent with sucrose accumulationtrend before flowering period, which shows that SS gene associated with other enzymes isresponsible for the synthesis of sucrose synthesis, and after flowering period, SS gene mainlydecompose sugar. With its decreased expression, decomposition of sucrose decreased andsucrose accumulated. In common sorghum, in the prophase of sucrose synthesis, SS geneexpression decreased, stopping the sucrose form synthesizing. After that, with the expressionSS gene increases, decomposition of sucrose ability strengthen, which leads to the lowsucrose content compared with sweet sorghum. Therefore, the differences of SS expression islikely to be the key factor causing the difference of sugar content in sweet sorghum andordinary sorghum, regulating sucrose accumulation.4. Analysis the differences between experimental data for two years by SPSS software, theresults show that the difference was not significant, and the experimental results is accurate,has the repeatability and don’t influenced obviously by environmental conditions.