Identifying AFLP and microsatellite markers for vernalization response gene Vrn-B1 in hexaploid wheat using reciprocal mapping populations

Marker-assisted selection may be useful for combining specific vernalization response (Vrn) alleles into a single wheat genotype for yield enhancement; however, DNA markers are only available for two of the three genes identified to date. The objectives of this study were to investigate reciprocal effects on days to heading using F₂ populations generated by cross-hybridizing near-isogenic lines (NILs) carrying spring (Vrn-B1; TDB) and winter (vrn-B1; TDC) alleles, and to identify markers linked to Vrn-B1 through genetic linkage analysis. Heading data were recorded for 91 and 89 progeny from reciprocal mapping populations TDB/TDC and TDC/TDB, respectively, and significant (P < 0.0001) reciprocal and dominance effects were detected. Among 207 amplified fragment length polymorphisms primer pairs and seven wheat microsatellite markers screened, two and one, respectively, were linked distally to Vrn-B1 on wheat chromosome 5BL Microsatellite Xgwm408 was most closely linked to Vrn-B1 at 3.9 and 1.1 cM in the TDB/TDC and TDC/TDB map, respectively. Reciprocal differences in recombination distances emphasize the importance of female parent choice when generating mapping populations. Molecular markers are now available for three Vrn loci in wheat.