Induction of cytoplasmic male sterility in the seed progeny derived from artificially-synthesized interspecific chimera in Brassica

We produced artificial interspecific chimeras by in vitro grafting, and obt ained cytoplasmic male sterile (CMS) variants in the seed progenies derived from backcrossing the chimera with one of the mother plants, B. campestris cv. Komatsuna. The induced CMS has been stably inherited by crossing it wi th 'Komatsuna', not with 'Ruby Ball' cabbage. The nuclear component of CMS is complete 'Komatsuna' type in morphology, chromosome number (2n = 20) and Southern blot using ribosomal 17S RNA gene as a probe. PCR analysis by usi ng mitochondrial atpA primer showed the complete 'Ruby Ball' type, suggesti ng nuclear-cytoplasmic exchange. However, Southern blot patterns were diffe rent among those of the CMS and both parents by using atpA. Recombination o r some unknown change is supposed in the mitochondrial genome via the proce sses of synthesis and propagation of the chimeras.