The Sequence Polymorphism Of MeSuSy1and Its Affects To Starch Accumulation In Storage Root Of Cassava

Cassava(Manihot esculenta Crantz)is one of the top three root and tuber crops in the world,featured by high yield potential and starch accumulation ability.It is an important source of industrial starch and fuel ethanol,a vital source of food for people in Africa,and an important animal feed in the tropics.It is essential demanding to understand why high efficient starch accumulation in cassava for cassava breeding and industry development toward to genome selection breeding.A set of 11 varieties(lines)include of SC205,SC5,SC8,Arg7,Rayong9,KU50,91,R3,17Q,FB-1 and FB-4 was selected use for evaluation of biomass accumulation and expression analysis of genes involved in starch accumulation under field condition of Wenchang County in Hainan.The results showed that:The chlorophyll content,net photosynthesis ratio,dry matter content of storage root and expression level of tested genes at three developing stages exhibited significant difference among various varieties(lines);FB-1,SC5,SC8,KU50 and Rayong9 displayed higher bioaccumulation and storage root yields at torage root mature stage;The chlorophyll content reached its peak and displayed significantly positive correlation with net photosynthesis ratio at enlargement stage,but no significant correlation with yield and other physiological index.The MeSUTl has high expression in the storage root forming and enlargement stages,and MeSMuSy1 kept high expression in storage root forming,fast enlargeing especially in storage root mature stage.Correlation analysis indicated that the expression level of MeAGPSl(formation stage)and MeGBSSl(formation and enlargement stage)have significantly positive correlation with the dry matter content of storage root(enlargement stage),and the expression level of MeSBE2.2 has significantly positive correlation with the dry matter content of storage root in mature stage.Sucrose transporters(SUTs)are mediated in sucrose's phloem loading,and its unloading to diverse sinks,which then play an important physiological role in carbohydrate partitioning.The promoter and encoding region of MeSUT1 were cloned in the 11 different cassava varieties(lines)separatively,the polymorphism of AMeSUT1 were then detected through sequence alignment.18 promoter sequences and 19 coding sequences of MeSUT1 gene were got from 11 cassava varieties(lines),that is,at least found double sequences from each of 8 varieties shown the high heterozygostics of cassava.The main variations were detected within the promoter,and 9 haplotypes were indentified at the promoter region.Sucrose synthase is the first step in the conversion of sucrose to starch.The polymorphism of MeSuSyl was also detected in the 11 different cassava varieties(lines)by cloning and repeated sequencing.22 different promoter sequences and coding sequences of MeSuSyl were got from 11 cassava varieties(lines).The results of the multisequencing alignment of sequences concluded that not only base mutations but single base InDels and a short repetitive sequence InDel exist in the promoter region of MeSuSyl gene,with only base substitution in the coding region.Five and one haplotype blocks were identified at the promoter and coding region,respectively.5 CAPS(PCR-RFLP)markers and a InDel marker were developed to distinguish the MeSuSy1 haplotypes,a cassava nature population with 136 lines were genotyped at the MeSuSyl loci use these markers,and then used for haplotype association analysis.The results showed that two haplotypes(Hap-A,Hap-H)in the MeSuSyl promoter region have significantly positive correlation with yield,a haplotype Hap-R in the MeSuSyl promoter region and a haplotype Hap-N in the MeSuSyl coding region have significantly positive correlation with dry matter content of storage root.This study we developed that the haplotypic markers in MeSuSy1 of cassava first timely,will be important for breeding super high yield and high quality varieties by genome selection in cassava.