Tagging of resistance gene(s) to rhizomania disease in sugar beet (Beta vulgaris L.)

The rhizomania disease is one of the most important diseases in Iran and some other parts of the world which potentially could play a role in decreasing sugar yield in fields. One approach to combat with this disease is the use of resistance varieties. This varieties have been identified which are having resistance genes to rhizomania disease (i.e. Rz1, Rz2). In order to use these genes in breeding programs (MAS) tagging these genes with molecular markers is necessary. In our study, we used infected soil which was provided from infected fields then greenhouse test was done to identify resistance and susceptible plants. Extracted DNA from leaves of resistant and susceptible plants was bulked to provide two bulks for resistance and susceptible plants. Three-hundred RAPD primers were used in analysis of the two bulks and two F2 populations. One population was obtained from a cross between Holly1-4 as resistance parent and an annual variety as susceptible plant. The second population was constructed by crossing between WB42 as resistance parent and L 261 as susceptible one. Finally genes were tagged using two RAPD primers and one of the markers is OP-091150 which is 27 cM apart from Rz1 gene in coupling phase. The second marker is OP-AN9600which is 13.7 cM apart from Rz1 gene and in repulsion phase.   Key word: Sugar beet, rhizomania disease, resistance gene, RAPD marker