Genetic Characteristics of Frizzled and Incomplete Frizzled Feather and SNP Detection of KRT75 Gene

The study was mainly focused on the genetic characteristics of frizzled feather trait,the phenotype difference between frizzled feather（FF）and incomplete frizzled feather（IFF),and SNP analysis of the candidate gene KRT75 in the frizzle and incomplete frizzle chickens of different feather colors,which could provide scientific gist for the frizzle gene mapping,development and utilization of the two kinds of chicken.The resource population（homozygous Yellow feather Kirin chicken×Huaixiang chicken）of hybrid F2 was established.The back,neck,wing primary and wing-bow feather were observed and the scatter diagram of rachis bending degree was drawn.The blood of 10 white frizzle feather Kirin（WFF）chicken,10 Yellow frizzle feather Kirin（YFF）chicken,10 Royal,25 Yellow feather incomplete frizzle（YFIF）chicken and 15 Black feather incomplete frizzle（BFIF）chicken from homozygous WFF chicken×Royal chicken of hybrid F1 were extracted,then the DNA of those samples were extracted.The primer of KRT75 was designed,the PCR products were also sequenced after purification,Chromas 2.22 and DNAMAN software were used to analysis of sequence peaks photos and sequence alignment,respectively.The amount of orthogonal and reciprocals cross in hybrid F1 was 127 and 139, respectively, which all were the slight（incomplete）frizzled feather phenotype,with no different penetrance.The resource population of hybrid F2 were consisted of 55 frizzle chicks including some hens and cocks,106 incomplete frizzled and 68 contour feather chicken,the proportion of which was coincided with Mendelian segregation ratio of 1:2:1 by χ²-test（P>0.05),therefore it preliminary verified that the frizzle gene F was autosomal incomplete dominant inheritance.FF and IFF curved upward deviating from the skin,and the line slope of trend line of FF was 3.5 times than that of IFF.It found that there was no 69 bp deletion mutation in exon 5 region of KRT75 gene in WFF and YFF chicken,but 3 SNPs（T71C,T83C,C95T）were deleted in the 69 bp,which were homologous CC in WFF and YFF chicken,of two were heterozygous in YFIF chicken,while all were heterozygous in BFIF chicken.2 SNPs（T662C and T770C）were also deleted in exon 6,heterozygous of which were only deleted in BFIF chicken.The haplotype analysis indicated that 9 haplotypes were detected in 60 individuals,hap1/hap1 was specific genotype of WFF and YFF chicken.The haplotypes of two incomplete frizzle feather chicken were apparently different,hap4 was specific haplotype of YFIF chicken,while hap6,hap7,hap8 and hap9 were specific haplotypes of BFIF chicken.The frizzle gene F was autosomal incomplete dominant inheritance,there were obvious differences between FF and IFF traits,5 SNPs in exon 5 and 6 of KRT75 gene probably were the reference of molecular markers as distinguishing between frizzle and incomplete frizzle chicken.