关键词: 冬小麦, 淀粉糊化, SNP标记, GWAS, 单倍型, 候选基因

Abstract:

【Objective】 Starch is the main component of wheat kernel and plays an important role in processing. The gelatinization characteristic of starch is an important index to evaluate its quality. The genetic variation of starch gelatinization was studied to provide basis for improving wheat quality. 【Method】 Seven starch gelatinization traits, including gelatinization temperature, peak time, peak viscosity, trough viscosity, final viscosity, decay value and recovery value, were phenotypically determined in 205 winter wheat varieties. Genome-wide association analysis was performed using 90K chip, and haplotype analysis was performed on the stable and significant sites found. 【Result】 The seven characteristics, such as pasting temperature, showed abundant variation in different environments, and the coefficient of variation of attenuation value was the largest (29.31%-31.14%). There were significant differences among genotype, environment and genotype × environment, and the generalized heritability was 0.69-0.86. Through genome-wide association analysis, we found 198 loci that showed significant associations with seven traits. It was distributed in 20 other linked groups except 6D chromosome. There were 58 sites that were stable in 2 or more environments, involving all 7 traits, such as pasting temperature (10), peak time (5), peak viscosity (12), trough viscosity (10), final viscosity (7), break down (4) and set back (10), which could explain 5.54%-22.21% of genetic variation, twenty-one new sites were identified. By haplotype analysis of multiple effector sites that exist in multiple environments and have high phenotypic contribution, Four haplotypes, Hap1 (66.84%), Hap2 (16.84%), Hap3 (9.70%) and Hap4 (6.63%), were found at Kukri_c17417_407 on chromosome 4A, which were significantly related to peak viscosity and break down. Where Hap2 is the peak viscosity and high break down. (P<0.0001). The distribution frequency of varieties (lines) containing haplotype Hap2 in different ecological regions was from high to low as Huanghuai winter wheat region>foreign varieties>Southwest winter wheat region>Middle and lower reaches of Yangtze River winter wheat region>Northern winter wheat region. There were 11 single cause multieffect sites, among which there were 3 multiple effect sites associated with final viscosity, set back, peak time and trough viscosity. Jagger_c4026_328 and other 11 stable genetic loci located on 1B, 2A, 3A, 3B, 4A, 4B, 5B and 6B were mined, and 11 candidate genes that might be related to wheat starch gelatinization traits were screened. 【Conclusion】 In this study, RVA parameters had high heritability, and the RVA parameters of wheat starch were different in different environments. In this study, RVA parameters had high heritability, and the RVA parameters of wheat starch were different in different environments. 58 stable loci were detected that were significantly associated with starch gelatinization traits, and 4 different haplotypes were identified on chromosome 4A that were significantly associated with peak viscosity and break down, and 11 candidate genes related to starch gelatinization were screened, which could provide help for marker-assisted high-quality wheat breeding.

Key words: winter wheat, starch gelatinization, SNP marker, GWAS, haplotype, candidate genes