Genetic analysis of Vrn genes and establishment of their DNA markers in wheat by using Single Nucleotide Polymorphisms (SNPs)

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Molecular genetic study has been conducted in the present study, and succeeded to establish molecular markers for the selection of four genes for vernalization response, Vrn-A1,Vrn2,Vrn-D1,Vrn4. The detail is given below for each gene.Vrn-A1 ; We could confirm the linkage (12.8cM) with RFLP locus Xwg908,at which CAPS marker was established.Vrn2 ; Linkage with a dCAPS marker of Xwg644-5B and SSR markers (Xgwm408 and Xgwm604) was detected, and four loci could be mapped as follows ; Vrn2-1.6cM-Xwg644-2.5cM-Xgwm408-13.8cM-Xgwm604. As a result, Vrn2 was located on chromosome 5B and we proposed to rename Vrn2 as Vrn-B1. Xgwm408 can be utilized as a practical selection marker of Vrn-B1, since it is closely linked with Vrn-B1 and clear polymorphism can be detected among the Japanese wheat cultivars and the foreign cultivars carrying Vrn-B1.Vrn-D1 ; Vrn-D1 is the most important gene for wheat breeding in Japan, since most of the wheat cultivars with spring growth habit carry this gene. Two SSR … More markers (Xgwm212 and Xgwm292) proved to link with Vrn-D1, at a distance of 4.6cM and 7.4cM, respectively. Although Xgwm292 was rather distantly located, it was highly polymorphic even in the Japanese early maturing cultivars. Therefore, this SSR marker can be utilized as a practical selection marker for the breeding of early maturing cultivars with spring or winter growth habit.Vrn4 ; Several SSR markers, such as Xgwm190,Xgdm3 and Xgwm292 located on 5D chromosome, were analyzed and close linkage (4.5cM) was detected among Vrn4 and Xgdm3. Independence between Vrn4 and Xgwm292, which is closely linked to Vrn-D1, was also confirmed. It was therefore concluded that Vrn4 is located near the centromere on the long arm of 5D chromosome and independent of Vrn-D1. Vrn4 proved to be a new class of vernalization response gene which was different from Vrn-1 orthologue gene, and we proposed to designate as Vrn-D5.Vernalization response genes causing the difference in the degree of winter growth habit were analyzed in DH populations derived from a cross between two winter type cultivars, Winter-type Abukumawase and Chihokukomugi, by using AFLP markers. As a result, three QTL was detected and one QTL was located on the short arm of 7D chromosome. The effect of Vrn-D1 was also suggested. Less