Novel Allele Variations Of The Vernalization Gene Vrn-1 In Common Wheat (Triticum Aestivum L.)

Florescence is a developmental important stage, which is complex and influenced by temperature, light, water and other factors in plants. Vernalization is a process of which cold treatment triggers or promotes the florescence for annual and perennial plants. Wheat is an important food crop in our country, and its adaptation to diverse growing conditions is associated with the different vernalization-response genotypes. According to the vernalization requirements, wheat accessions can be classified into three types, i.e., spring, facultative and winter wheat. It is well-known that there are many genetic variations which contribute to the wide distributions of wheat.Therefore, discovery and validation of new vernalization genes or alleles will be helpful for vernalization mechanisms, as well as for wheat molecular breeding.The main results of this study are as follows:1. One natural population composed of 192 landrace and commercial varieties all over the world is phenotyped in Yuanmou, and genotyped by using the Vrn-1 markers published previously. Four varieties with recessive alleles of vrn-A1 and vrn-B1, but dominant allele Vrn-D1, demonstrate facultative phenotype. Sequence analysis discovers one SNP (A/C) in the CArG-box motif of Vrn-D1 promoter of the four facultative varieties, which is consistent with previous report.2. Fourteen facultative wheat varieties are phenotyped without vernalization and genotyped. Four varieties of Ardito, Ji20, CMSBT and Xuzhou-14 demonstrate facultative phenotype, carrying recessive allele combination in all the three genomes (vrn-A1vrn-B1vrn-D1). Sequence analysis reveals four novel SNPs in the first intron of Vrn-A1 of the four facultative varieties, which consist of three haplotypes (Haplotypeâ… : GGTG; Haplotypeâ…¡: GATG; Haplotypeâ…¡: TGGA).3. The function of the four novel SNPs are validated by Q-PCR under different time intervals of low temperature. The expression levels of Vrn-1 in winter variety Lu-14 increase gradually under 4w treatment, significantly higher than the facultative varieties, indicating that the winter variety is more sensitive to low temperature. The sensibility of facultative varieties to low temperature is weaker than the winter variety, and the expression levels of haplotypeâ… andâ…¡are signaficantly higher than that of haplotypeâ…¢.4. Segregation populations of F2 were developed previously by crossing the four facultative lines with winter line Lu-14. The phenotypes of individuals are assayed also under condition without vernalization. The segregation ratio of 3:1 only occurs in the individuals in F₂ population of Ardito×Lu-14 between the no jointing plants and the jointing plants (χ² test, p<0.01), suggesting winter habit is controlled by a single dominant gene in this F₂ population.