The Analysis Of Characteristics Related To Grain Hardness Of Wheat Varieties (Strains) In Huanghuai Region And Snps Of GSP-1 And Its Relationship With Kernel Hardness

Wheat kernel hardness is a very important parameters used in wheat breeding and quality study,the classification and pricing of wheat. Wheat kernel hardness is also an critical factor in the food processing quality and milling characteristics. Therefore, the study of genetics of wheat grain hardness genes is of great significance to the improvement of wheat quality. In this study, the hardness, grain diameter, moisture content, thousand-kernel weight of 231 wheat varieties (lines) in Huang-Huai region were tested by SKCS. Gsp-1 genes were isolated by PCR and the correlation of SNP variations of Gsp-1 genes and wheat kernel hardness was studied through Spearman rank correlation coefficient. The main results are as follows:1. The hardness, grain diameter, moisture content, thousand-kernel weight of 231 wheat varieties (lines) in Huang-Huai region were tested by SKCS and the results are as follows: the number of soft wheat which the value of SKCS was under 40 were 15; there were 37 mixed wheat varieties which the value of SKCS is between 40 and 60; there were 181 hard wheat varieties which the value of it was equivalent to or greater than 60. The three types accounted for 6.5%,16% and 77.5% respectively.The result of this study shown that the main type of wheat varieties (lines) in Huang-Huai region were hard and semihard wheat. The correlation analysis of wheat quality traits indicated that there was a significant negative correlation between hardness and moisture content(-0.5192)and a significant correlation between hardness and thousand-kernel weight(0.4624) which indicated that thousand-kernel weight can by elevated by the increase of hardness,while increasing moisture content can decrease hardness.2. Specific fragments of Gsp-1 about 650 bp containing the full coding regions of grain softness protein-1(Gsp-1) were amplified from 50 varieties(lines) using a primer pair Gsp-1F/Gsp-1R designed according to the conserved region of grain softness protein-1(Gsp-1)published in the GenBank. The positive clones were indentified by colony PCR and then sequencing. Sequence analysis with DNAMAN showed that the length was 495bp and encoded 165 aa amino acid residues and there was no intron in the CDS which contained the typical singal peptide containing 19aa, 10 conservative Cys. Puroindoline protein was rich in Trp domains which integrated with the surface of starch,which worked on the grain texture and then influenced the wheat kernel hardness. While there was no puroindoline-like Trp domain in the Gsp-1 protein and the analysis of Gsp-1 protein found that 2 Trp existed between the 3rd and 4th Cys, which hardness of Gsp-1 protein may be effected by them. Gsp-1 genes can be classified in to 3 types named Gsp-1a,Gsp-1b and Gsp-1c according to Rahman. Secondary structure analysis of Gsp-1 gene showed that Gsp-1a could form 4α-helixs and Gsp-1b could form 5α-helixs. The two conservative Try were between twoα-helixs.3. According to the result of wheat kernel hardness, 50 out of 231 varieties(lines) and 103 materials downloaded from NCBI were used to conduct gene sequence alignment.In the 50 varieties(lines), the hardness of 35 materials were greater than 60 and the hardness of 10 materials were between 40 and 60 and the rest of it were under 40. The result of sequence alignment indicated that the homology reached to 97.21% and further analysis found that there were 98 variant sites in the 153 sequences. 72 sites were single mutation, 26 polymorphism.Therefore the 26 polymorphism can be regarded as candidate SNPs from which 17 SNPs riched in variations were underlying datas. Although the hardness can vary dramatically,the study of correlation between SNPs and the value of SKCS demonstrate that there was no correlation between SNP sites and grain hardness.