PRODUCTION OF APOMICT-LIKE SEEDLING THROUGH INTERGENERIC CROSS BETWEEN JAPANESE PEAR AND APPLE BY MEANS OF POLLEN IRRADIATION

Abstract

Apomixis may provide a new possibility for pear genetics, breeding and propagation. In this experiment we tried to produce apomictic seedlings in Japanese pear through an intergeneric cross between Japanese pear and apple by means of pollen irradiation. The false hybrid can be efficiently selected in this intergeneric crossing. Because the true intergeneric hybrid potent genetic lethal system, only the false hybrid with the possibility of apomixis should survive in the crossing. Japanese pear (Pyrus pyrifolia Nakai) ‘Kousui’ and apple (Malus pumila Mill.) ‘Fuji’ were used for the intergeneric cross. The apple pollen was irradiated by gamma ray from 60Co and pollinated on the Japanese pear. A total of fourteen intergeneric seedlings at 10Gy/h (50 and 80Gy) and 20Gy/h (60 and 120Gy) developed from 155 seeds, and an individual at 80Gy (10Gy/h) and five individuals at 120Gy (20Gy/h) survived without exhibiting lethal symptoms. Plant type and morphological characters of five apomict-like seedlings at 120Gy were similar to those of Japanese pear. Their RAPD markers were only inherited from Japanese pear and their DNA contents estimated by FCM were also similar to those of Japanese pear. From the above results, we conclude that five apomict-like seedlings may be true apomicts in Japanese pear.