Abstract
Plants resistant to soft rot disease were produced by in vitro-mutagenesis and -selection using a microspore culture system in Chinese cabbage. The effect of ultra-violet (UV) irradiation on microspore embryogenesis was investigated. Embryo production decreased with increasing duration of UV-irradiation and the LD50 was estimated to correspond to an exposure of 12 s. Culture filtrate of soft rot bacteria caused a reduction of embryo formation from microspores and plant regeneration from microspore-derived embryos, suggesting that the culture filtrate is phytotoxic. After 6, 657 embryos derived from UV-irradiated microspores were selected on a medium containing a soft rot culture filtrate, 250 plantlets were regenerated. When their progenies were assessed for resistance to soft rot disease, three lines showing a markedly increased resistance to the disease were obtained. The resistant plants are considered to be mutants produced by in vitro-mutagenesis.
