A new RAPD marker for beet necrotic yellow vein virus resistance gene in Beta vulgaris

RAPD markers linked to beet necrotic yellow vein virus (BNYVV) resistance genes were identified in two Beta vulgaris accessions Holly-1-4 and WB42 using bulked segregant analysis. The polymorphism revealed by the RAPD markers in the F2 generations of WB42 was higher than that of Holly-1-4. The segregation distortion at marker loci was slightly lower in the B. vulgaris × B. maritima cross than in the B. vulgaris × B. vulgaris cross. For Holly-1-4, a RAPD marker was identified in a long distance from the resistance gene of Rz 1 . However, a RAPD marker tightly linked with Rz 2 gene in repulsion phase was detected with an approximate distance of 0.036 rf. This marker was not generation specific and showed high repeatability. The distance between Rz 1 and Rz 2 genes was estimated as 0.464 rf. After the Rz 2 Rz 2 and Rz 2 rz 2 genotypes were identified using ELISA values and repulsion phase RAPD markers, comparison of their ELISA means revealed lack of the gene dosage effects. Nevertheless, under the field or severe infection conditions, the difference between ELISA mean values of the Rz 2 Rz 2 and Rz 2 rz 2 genotypes might be more than that observed in this study and the gene dosage effects of Rz 2 allele might be important.