We have examined the inheritance of 20 rapeseed (Brassica napus)-specific RAPD (randomly amplified polymorphic DNA) markers from transgenic, herbicide-tolerant rapeseed in 54 plants of the BC1 generation from the cross B. junceax(B. junceaxB. napus). Hybridization between B. juncea and B. napus, with B. juncea as the female parent, was successful both in controlled crosses and spontaneously in the field. The controlled backcrossing of selected hybrids to B. juncea, again with B. juncea as the female parent, also resulted in many seeds. The BC1 plants contained from 0 to 20 of the rapeseed RAPD markers, and the frequency of inheritance of individual RAPD markers ranged from 19% to 93%. The transgene was found in 52% of the plants analyzed. Five synteny groups of RAPD markers were identified. In the hybrids pollen fertility was 0-28%. The hybrids with the highest pollen fertility were selected as male parents for backcrossing, and pollen fertility in the BC1 plants was improved (24-90%) compared to that of the hybrids.
In order to optimize shoot regeneration in Kalanchoe¨blossfeldiana, leaf and internode explants of seven cultivars including one inter-specific were studied. The effects of various combinations of a-naphthalene acetic acid (NAA) (0, 0.57 M) and thidiazuron (TDZ) (0, 0.45, 4.5, 22.5, 67.5 lM) on MS medium were examined. In all cultivars shoot regeneration frequency and number of shoots per explant were enhanced by increasing TDZ concentration. Supplementing the media with NAA did not improve shoot regeneration. Maximum regeneration frequency and optimum concentration of TDZ for shoot regeneration depended significantly on the cultivar. Internode explants, but not leaf explants, of some cultivars, were able to produce adventitious shoots without treatment with growth regulator.
Eight clones of repetitive DNA were isolated from Crocus vernus Hill. The genomic organization of the clones was analyzed by in situ hybridization to C. vernus and Southern hybridization to a range of Crocus and other species. Seven clones were used for in situ hybridization. Sequence analysis showed that all eight clones were nonhomologous, and thus represented eight different sequence-families. In situ hybridization showed that six were dispersed in high copy numbers on all chromosomes of the C. vernus genome, whereas one was localized proximal to the secondary constriction, at the NOR (nucleolar organizer region) and was not further analyzed, as it was considered part of the 18S-25S rDNA repeat. Except for short palindromes, none of the sequences showed notable internal structures. Clone pCvKB4 showed homology to the reverse transcriptase gene of Ty1-copia-like retrotransposons; the others showed no homology to known sequences. When used as probes for Southern hybridization, four showed a ladder of 3-4 bands superimposed by irregular patterns, indicating organization in short tandem arrays. Each clone had a unique distribution among Crocus species (12-16 species analyzed with each clone) and six species of Iridaceae, Liliaceae, and Amaryllidaceae; all seven investigated sequences were Iridaceae specific and four were Crocus specific. The species distribution of these seven clones showed notable discrepancies with the taxonomic subdivision of the genus at the subgenus, section, and series levels. The results suggest that the phylogeny and taxonomic structure of the genus Crocus might need reconsideration. The analysis of repetitive DNA as a major and rapidly evolving part of the genome could contribute to the study of species relationships and evolution.
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