Gene Clone And Function Research Of Sucrose Transporters Gene Family In Sweetpotato (Ipomoea Batatas(L.) Lam)

Sweetpotato (Ipomoea batatas (L.) Lam) is one of the most important crops in the world, which has rich nutritious and high production. In the field, if the ground part is excessive growth, the yield will be lower. The phenotypic had close relationship with photosynthetic product transportation. The "sink-source" regulation is complex and the problem is still unresolved. Our research was focused on the "flow" of photosynthetic product transfer, part of the "sink-source" process. In order to explore the regulatory mechanism of sucrose transport, we focused on the sucrose transporters. In the paper four IbSUTs genes was cloned, in order to find out the function of these IbSUTs in sweetpotato source transportation, we analyzed the expression level of IbSUTs in five varieties based on the qRT-PCR technology. Studies on sucrose transporters may enable us to better understand the molecular mechanism of sucrose transport.(1) In the present study, IbSUT3 and IbSUT4 genes were cloned from sweetpotato of Jishu25 by degenerate PCR and rapid amplification of cDNA ends (RACE) techniques, then sequence information of IbSUTl and IbSUT2 from NCBI database was despotized. The features of IbSUTs including isoelectric point, theoretical mass, identity of nucleotide, identity of amino sequence, homology of amino acid, trans-membrane domain prediction and phylogenetic construction were analysed by bioinformatics. Phylogenetic analyses showed that IbSUT1, IbSUT2, IbSUT3 belongs to Group I and IbSUT4 belongs to GroupⅣ.(2)According to previous research, the sucrose transporter gene has different function and the expression level is different. QRT-PCR was performed to determine the transcript levels of IbSUTl, IbSUT2, IbSUT3 and IbSUT4 in five varieties including Jishu25, Jishul8, Nonglin57, Xushu32 and Gungshu87. The IbSUT1 expression level was 10 fold higher in Guang87 than the other varieties, especially in leaves and stem. The expression of IbSUT2 had remarkable difference in root of different varieties, however the expression level of IbSUT3 and IbSUT4 was insignificant in different varieties. Expression pattern analysis of guangshu87 and jishu25 showed that IbSUTl and IbSUT2 express highest in leaf. Highest expressed in stem and leaf were agree with the features of sucrose transporter. The experiments of nitrogen treatment and uniconazole treatment on Jishu 25 was implemented to further verify the function of these genes. The expression level of IbSUTl in stem was increased with elevated concentration of nitrogen treatment. When it was treated by uniconazole, the expression level of IbSUTl in stem was increased too. In the two experiment above the production was increased and the IbSUTl expression level in the stem were elevated too.(3)In order to further research the function of IbSUTs gene, the fusion vector of pBI221-IbSUTl-GFP and pBI221-IbSUT2-GFP was constructed and transformation into Arabidopsis protoplast, which proved IbSUT1 and IbSUT2 located on the plasma membrane.(4) The over-expression vector of pSTART-IbSUTl was constructed to explore the function of IbSUTl, then it was transformation into agrobacterium EHA105 and infected into Arabidopsis. We got the F1 generation of transgenic Arabidopsis.