Searching for resistance genes to Venturia inaequalis in wild and domestic apples in Iran

Scab caused by the fungus Venturia inaequalis (Cook) G. Winter is the most devastating disease of the apple worldwide. To control the disease most efforts have been directed toward the breeding programmes by introgression of scab resistance genes from wild apples into commercial cultivars. Although, various apple genotypes exist in Iran, no comprehensive data regarding the possible presence of scab resistance genes is available. In this research the presence of five R genes (Rvi2, Rvi4, Rvi6, Rvi8 and Rvil1) was assessed in 28 wild and domestic apple genotypes using 13 SCAR and SSR markers. Sequencing and blastN results confirmed the identify of Rvi2, Rvi6, Rvi8 and Rvil1 genes. Based on the results, wild apples had more resistance genes and among foreign and autochthonous apples, 'Golden Delicious', 'Malayer-1' and 'Shahroud-6' carrying at least three R genes categorized as almost tolerant cultivars. However, 'Gala', 'Boshghabi-e Damavand', 'Manouchehri' and `Golab' had just one R gene and classified as susceptible cultivars. The most frequent scab resistance breeding programmes rely on Rvi6 gene (HerVf2 gene), which was also detected in this study in crabapple Malus floribunda providing a rich resource for developing resistant apple cultivars in Iran.