|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1994 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1993 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1992 : ¥1,200,000 (Direct Cost : ¥1,200,000)
About one hundred intergeneric hybrids between Japanese pear and apple have been bred by means of seedling and embryo culture to cross reciprocally using three Japanese pear cultivars, 'Osa-Nijisseiki', Kikusui', 'Kosui', and three apple cultivars, 'Fuji', 'Tsugaru', 'Orin'. The hybrids were also obtained effectively from the cotyledons, which shoot did not formed by embryo culture, using jointly with the method of adventitious bud induction.
Morphological characters of the shoots and leaves, anthocyanin development of the stems and leaves, photosynthesis and graft-compatibility of these intergeneric hybrids were similar to those of mother plants in general. However, the genes from the father plants like an anthocyanin synthesis or an improvement of the graft-compatibility to the rootsocks of father's genus were introduced to the hybrids. Photosynthetic activities of these hybrids in own roots were low in general, but those of the grafted hybrids were recovered the same levels of mother
The investigation of the inheritance of susceptibility to black spot disease of Japanese pear and Alternariablotch of apple in these hybrids revealed the interesting segregation in hybrids of Japanese pear to cross apple pollen, and the resistance against both diseases in the hybrids of apple to cross Japanese pear pollen. Testing of apple scab disease in these hybrids showed the resistance in the all hybrids of Japanese pear to cross apple pollen and the resistance in the seven hybrids of apple to cross the pear pollen. These results offer some important criteria on the new breeding strategy for disease resistance using intergeneric hybrids.
In order to obtain the somatic intergeneric hybrids by protoplast fusion, the factors affecting of protoplast isolation and culture and the methods of protoplast fusion by the polyethylene glycol fusion and the electric fusion. The culture system from protoplast to callus was established. However, the breeding of the somatic hybrid could not succeed due to the low frequency of regeneration from callus. Less