| Cassava,one of the world's three major root crops,has been praised as the "king of starch",and is mainly distributed in Guangxi,Guangdong,Yunnan,Hainan and other regions of China,and has cultivated more than 24 million hectares in the world.Due to its high photosynthesis efficiency and high starch accumulation,Cassava is considered an important food crop and energy crop.Sucrose synthase is the first key enzyme in the starch biosynthesis metabolic pathway.It can reversibly catalyze sucrose and UDP to produce UDPG and fructose.UDPG is a substrate for starch synthesis.Sucrose synthase activity significantly affects the sucrose content and starch synthesis efficiency in plants and is a measure of sink strength in crops.The Susl gene was the most highly expressed member of sucrose synthase gene family in cassava storage roots.This study was over-expressed the cassava Susl gene in potato and created a new high-starch potato germplasm.China is the largest importer of potato starch,and the demand for high-quality potato starch is particularly prominent.Therefore,the development of new germplasm of high-starch potato has good application prospect and practical significance.There are few studies on starch accumulation related to sucrose synthase gene in cassava root,and the research of cassava sucrose synthase 1 breeding new germplasm of high-starch potato is in blank.This study further promotes the research field of transgenic high-starch potato,and has a positive effect on the research status and development of the transgenic potato filed.In this study,the Susl gene was cloned to construct an overexpression vector,CaMV35Spro::MeSus1.Basta resistant regenerated potato plants were obtained by potato genetic transformation technique.DNA and RNA levels of the regenerated potato plants were detected.Transgenic Susl potato plants were identified.After propagation,transplanting and harvesting,the physiological and biochemical indexes of potato tubers carrying Susl gene were detected in harvest period.According to the determination of the dry matter,starch,and reducing sugar content of transgenic Susl potato plants tuber,the preliminary scientific basis for the transformation of MeSusl gene to createnew germplasm of high-starch potato was provided.The results of this study are as follows:1.Constructed an over expressed vector for gene,CaMV35Spro::MeSusl.2.Through the potato genetic transformation technology,62 regenerated potato plants were obtained.These transgenic lines were detected in DNA and RNA levels,and qRT-PCR was used to detect the expression level of MeSusl gene.Finally,10 transplanting MeSusl transgenic lines(B1-B10)were identified.3.The physiological,biochemical indexes of transgenic potato lines and wild potato plants were investigated.The reducing sugar content of tubers of B1,B2,B7 and B10 transgenic lines was higher than the wild control group.The reducing sugar content of tubers of B3,B4,B5,B6,B8 and B9 transgenic lines was lower than the wild-type control group.The tuber dry matter rate of the B1 line and the wild control group was 23.0%,and the dry matter rate of the other transgenic potato lines was between 18.0%and 22.0%,which was lower than the wild-type control group.The starch content of B1-B10 transgenic lines tubers was lower than the wild-type control. |
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