GENETIC CONSTITUTION OF GERM-CELLS IN INTERVARIETAL AND INTERSPECIFICCHIMERAS OF BRASSICA INDUCED BY IN-VITRO GRAFTING

The characteristics of intervarietal and interspecific chimeras synthe sized by the graft-culture method were determined by morphology, antho cyanin pigmentation pattern, and crossing. In an intervarietal chimera between 'YR-ranpou' (green cabbage) and 'Ruby ball' (red cabbage) in Brassica oleracea, a segregation phenomenon was noted in which seeds g iving rise to purple and green plants were both produced in a single c apsule in F-1 progeny from crosses of chimeras with YR ranpou, the ant hocyanin-free graft partner type. The degrees of segregation varied, r eflecting the structure of the chimeras. YR ranpou-dominant chimeras p roduced capsules in which seeds gave rise to green plants at a high fr equency, while Ruby ball-dominant chimeras produced capsules in which seeds in one capsule gave rise to purple plants at a high frequency. M ixed chimeras produced capsules with green plants or purple plants mor e regularly than did other chimeral types. Furthermore, a chimeral typ e in which seeds gave rise to green and purple plants was found in 3.2 % of the total crosses. Segregation patterns in the progenies correspo nded with the chimeral types. Chlorophyll-deficient variation (resulti ng in variegation or the production of albino plants) was found at a f requency of 2.6%. These results show that chimeric tissues are actuall y in a mixed state and that either the ovary develops from more than t wo cells or else that variation occurs in the germ-cell layer. In inte rspecific chimeras between Ruby ball and Komatsuna (B. campestris) var ious types of chimeras generally showed low pollen fertility, few caps ules, and low seed-setting. Progenies from selves (geitonogamy), open crosses and crosses with the two parental species produce a predominan tly homogeneous genotype showing either the Ruby ball or the Komatsuna type. Only two crosses produced four interspecific hybrids which expr essed variations in their morphological and isozymic characters.