Sequence Variation Of Starch Debranching Enzyme Genes ISA And PUL And Their Association With Kernel Physicochemical Properties In Maize(Zea Mays L.)

The genes related to starch debranching enzymes,PUL and ISA,are vital for biosynthesis of maize starch.Researching for sequence variations and excellent allelic variations of these genes are helpful to reveal the evolution law of starch debranching enzyme gene and provide a powerful basis for the development of molecular functional markers.In this research,335 excellent inbred lines,68 maize landraces and 32 teosintes were used as tested material.The resequencing of four genes related to starch debranching enzyme,ISA1?ISA2?ISA3?and PUL,in three populations were performed.Then we analyzed the sequence variation of these genes between three populations and within inbred lines.The 12 kernel physicochemical properties,including seven gelatinization characteristic parameters,four thermodynamic parameters and starch content were menstruated.The association analysis was conducted by combining candidate genes with phenotypic traits to screen the excellent allele variation sites related to kernel physicochemical properties.The major results obtained were as follows:1.The analysis results of phenotypic data show that 335 tested inbred lines had extensive variations in 12 kernel physicochemical properties.Gelatinization characteristic parameters,thermodynamic parameters and starch content have significant different among inbred lines.The range coefficient of variation was from 1.31%to 76.5%,where peak temperature had minimum coefficient of variation and disintegration value had maximum coefficient of variation.The broad heritability of 12 traits ranged from 76.27%to 86.39%.In addition,the significant correlation between different traits were found.2.Sequence polymorphism analysis shows that 410 variation sites of ISA1 gene were detected in 335 tested inbred lines.These variation sites included 356 SNP and 54 InDel,where every 31.26bp had a SNP and every 206.11bp had an InDel.For ISA2,a total of 128 variation sites including 118 SNP and 10 InDel were found,where every 33.8bp had a SNP and every 398.8bp had an InDel.For ISA3,a total of 497 variation sites including 429 SNP and 68 InDel were detected,where every 31.07bp had a SNP and every 196.03bp had an InDel.For PUL,a total 1305variation sites including 1025 SNP and 280 InDel were detected,where every 53.85bp had a SNP and every 197.15bp had an InDel.In teosintes,local varieties and inbred lines,the nucleotides polymorphism of the four related genes decreased in turn,which indicated that these genes were strongly selected.3.Association analysis indicated there are 16 significant locus associated with maize kernel physicochemical properties.Two significant loci associated with valley viscosity were detected on ISA1 gene,and one significant locus associated with disintegration value,starch content and recovery value respectively,explaining 5.20%and 7.06%phenotypic variation,among which SNP(G/A)at 7039bp contributed the most to valley viscosity.Four significant loci were located on ISA2 gene,of which three SNPS were significantly correlated with enthalpy,and the phenotypic contribution rate was 7.35%?13.38%.One InDel correlated with peak viscosity,explaining 9.60%phenotypic variation.Five significant loci were identified on ISA3 gene,among which the SNP at 10329 was significantly correlated with peak viscosity,and the phenotypic contribution rate was 8.42%?8.73%.One SNP was significantly correlated with enthalpy,and the phenotype contribution rate was 7.40%.One SNP was significantly associated with gelatinization temperature,and the phenotypic contribution rate was 7.29%.Two significant loci were associated with peak viscosity and enthalpy on PUL gene.The SNP at 32878 was significantly correlated with peak viscosity,and the phenotypic contribution rate was 9.74%.One InDel was significantly correlated with enthalpy,and the phenotype contribution rate was 9.48%.