Mapping of the Rpv Resistance Gene against Downy Mildew in Pea (Pisum sativum L.)

Downy mildew causes severe yield and quality losses in pea (Pisum sativum L.). Therefore, the development of downy mildew resistant varieties is of high priority for pea breeders. Within this study in total 335 F3 families from a cross of the highly susceptible green pea variety `Topaz´ with the resistant breeding line `Gen. 27´ were tested for resistance behaviour against Peronospora viciae f. sp. pisi to determine the genotype of the corresponding F2 parental plants. The ratio 94:161:80 for homozygous resistant, heterozygous resistant and homozygous susceptible F2 plants was not significantly different from 1:2:1, expected for the effect of a single dominant resistance gene. The resistance gene Rpv was mapped to linkage group 1 of the pea genetic map. This linkage group was saturated by molecular markers available from literature. The marker AD147 was identified as nearest proximal flanking marker with 4.4 cM distance, and in distal position marker AB28 with 18.8 cM distance. Further marker saturation using the syntenic relationship of P. sativum and Medicago truncatula was not effective. The usefulness of the identified markers for marker assisted selection has been confirmed in independent pea breeding material and the results of this study should lay the basis for future fine mapping studies.*