Preliminary Report on Transfer Traits of Vegetative Propagation from Wild Rice Species to Oryza sativa via Distant Hybridization and Embryo Rescue

Abstract

There are diversified patterns of vegetative propagation in Oryza spp. If Oryza sativa is changed from annual type to perennial type via vegetative propagation, the perennial cultivar would be environmental sound and economical viable. There would be a great potential to increase rice harvest area via ratoon cropping or stubble cropping and some hope to break yield plateau via fixing heterosis by vegetative propagation. Another advantage is that it would shorten the time interval from hybridization to form fixed lines. A possible donor of the trait for ratoon or stubble cropping is O. rufipogon. The other species possessing rhizome formation ability for breeding of perennial rice are O. longistaminata, O. officinalis,
O. rhizomatis and O. australiensis. In this study perennial trait was transferred from wild species O. longistaminata, O. rhizomatis and O. officinalis to cultivated rice (O. sativa) through distant hybridization. Genotypes of O. sativa and wild species, pollen fertility of male species and environmental factors could contribute to crossability or germination rate of the resulting embryos. Finally “false” hybrid problem and research on utilization of vegetative propagation in wild rice species were discussed.