Gene Cloning And Molecular Markers Development Of Starch Biosynthesis Genes From Sweetpotato (Ipomoea Batatas(L.)Lam)

Sweetpotato(Ipomoea batatas(L.)Lam)plays an increasingly vital role in the area of function-food and food security.So starch breeding will certainly be a prime target..For the complexity of genome,the hexaploid sweet potato not only has complicated genetic background of Self-incompatibility,but it also has little EST information and minimal number of nucleic acid sequences.The research on the molecular biology lags behind the corn,wheat and other crops.We focused on the synthesis pathway of starch,cloned starch synthesis related genes and analyzed the expression of related genes in two resistance varieties.Studies on starch synthesis related syntheses may enable us to figure out the molecular mechanism of starch synthesis.And we use transcriptome sequencing data to develop molecular markers in order to apply to sweet potato breeding,accelerating breeding process.(1)IbSSS was cloned from luoxushu8 by homology cloning strategy according to the sequence information of morning glory from NCBI database.And we cloned IbGBSSI,IbISA,IbAGPase,IbSBEI,IbSBE? from zhengshu20 based on NCBI database.Then we use bioinformatics approaches to analyze these amino sequence including the secondary structure,the tertiary structure,relative molecular mass,the isoelectric point,transit peiptide prediction and functional motif.Furthermore,we analyzed the homology of amino acid from other plants and constructed the evolution tree.(2)According to the cloned cDNA sequence,the genome of IbSSS,IbGBSS?,IbAGPase,IbSSS from sweeetpotato of luoxushu 8 and zhengshu 20 were cloned.(3)We used qRT-PCR to study the transcript levels of IbGBSS?,IbSBE?,IbSBE?,IbISA in luoxushu8 and zhengshu20 which have a greater difference in starch content during in different storage root thickening periods.The expression level of IbSBE? and IbSBE? continued to rise.The expression level of IbSBEI in luoxushu8 was higher than in zhengshu20 during the same time period.The expression level of SBEII in zhengshu20 was higher than in luoxushu8 during the same time period.In the early stages of development,the kinetic trend of IbGBSSI expression levels was similar to IbSBE?,IbSBE? and IbISA.We assume that they jointly promote starch synthesis.(4)According to cloned eight genes from two varieties with different starch content,we compared each gene sequences and got some SNPs and Indels,but the experimental results of validation were unsatisfactory.(5)16 SNPs and 10 Indels were selected and verified on the basis of transcriptome data.The results showed that there are two SNPs and one Indel may be related to starch content.