Inheritance of high resistance to Venturia nashicola Tanaka et Yamamoto in Japanese pear (Pyrus pyrifolia Nakai) and Chinese pear (P. ussuriensis Maxim.)

Abstract

Inheritance of high resistance in Japanese pear 'Kinchaku' and Chinese pears 'Hong-li' and 'Mi-li' to pear scab caused by Venturia nashicola was examined, using hybrid seedlings of known parentage. The seedlings were inoculated with conidial suspension, and the resistance to scab was classified into three categories: highly resistant (HR), susceptible (S), or necrotic (N). Most progenies derived from crosses between susceptible cultivars were rated S, whereas progenies of S X 'Kinchaku' segregated into 1HR: 1S. Crosses between S X 'Hong-li' or 'Mi-li' produced HR, N, and S seedlings, which closely fit a 1HR: 1(N+S) ratio. Progenies derived from crosses between HR cultivars segregated into 3HR: I(N+S). The results support the hypothesis that HR phenotype in 'Kinchaku', 'Hong-li', and 'Mi-li' is controlled by a single dominant gene. The gene symbol Vn is proposed for the gene controlling HR phenotype.