Genetic map locations for orthologous Vp1 genes in wheat and rice

Chromosome locations for gene orthologues of the dormancy-related maize transcription factor VIVIPAROUS-1, encoded by the Vp1 locus on maize chromosome 3, were determined in wheat (Triticum aestivum L.) and rice (Oryza sativa L.) via linkage to markers on existing molecular maps using a cDNA of a wheat Vp1 orthologue as a probe in genomic Southern analyses. Vp1-orthologous loci were detected on the long arms of wheat chromosomes 3A, 3B and 3D [Xlars 10 (taVp1) loci] and rice chromosome 1 (osVp1), in line with previous evidence of synteny between these regions of the rice and wheat genomes and chromosome 3 of maize. The wheat loci mapped some 30 cM from the centromeres and some 30 cM proximal to the red grain (R) loci that control seed colour and coat-imposed dormancy. This unequivocal, genetic separation of the Vp1 and R loci may offer an opportunity for improving resistance to pre-harvest sprouting in wheat by combining the coat-imposed dormancy associated with red seed colour and true embryo dormancy regulated by Vp1.