PRODUCTION OF NEW INTERGENERIC HYBRIDS BETWEEN RAPHANUS-SATIVUS AND BRASSICA WILD-SPECIES

Intergeneric reciprocal crosses between Raphanus sativus and three Bra ssica species, such as B, fruticulosa (ssp, cossoneana strain 201 and ssp, mauritanica strain 401), B, maurorum and B, oxyrrhina, were carri ed out in order to analyze their crossability and to produce their Fl hybrids, Crossability was analyzed based on the pollen germination ind ex (P. G. I.) and the development of hybrid embryos which was evaluate d in vivo by conventional crossing and in vitro by ovary culture, When R. sativus was used as the pistillate parent, pollen grains of the Br assica species germinated well on the stigmas while only a small numbe r of pollen tubes could elongate near the ovules in a few R. sativus p istils, resulting in a low development of hybrid embryos, Using the Br assica species as the pistillate parent in the intergeneric crosses, t he crossability was relatively higher than that of the reciprocal cros s, When R. sativus was used as the pistillate parent, one F-1 hybrid w as produced by embryo culture in the cross of R. sativus x B. fruticul osa -401, When the Brassica species were used as the pistillate parent , 200 F-1 hybrids were obtained through ovary culture followed by embr yo culture from all cross combinations and 12 F-1 hybrids were obtaine d in the cross of B, oxyrrhina X R, sativus by conventional crossing w ithout embryo rescue, F-1 hybrids were intermediate between their pare nts in several characteristics except for flower color and root thicke ning, In the cross of the Brassica species X R, sativus, 12 amphihaplo id F-1 hybrids formed trivalents and a number of bivalents at metaphas e I (MI) and their pollen fertility ranged from 0 % to 70.2 %, Induced 6 amphidiploid F-1 hybrids showed relatively stable chromosome associ ations at MI and a higher pollen fertility than that of the correspond ing amphihaploid, It is suggested that these new F-1 hybrids could bec ome valuable materials in the breeding of the tribe Brassiceae.