| A modified system of in vitro approach-grafting was established in the present study, and was applied to synthesize chimeras between tuber mustard (Brassica juncea) and cabbage (Brassica oleracea). Effect of plant growth regulators on chimera formation was analyzed. The botanical and cytological characteristics of chimeras were studied as well. This research provided an excellent system for some basal theories such as tuber swelling, cell to cell interaction, plant tissue and organ development. At the same time, this system offered breeders a novel breeding way. The results were summarized as follows:(1) A modified system of in vitro approach-grafting was established, and was applied to synthesize chimeras between tuber mustard and cabbage. It offered a simple and convenient method for chimera formation. NAA and 6-BA were necessary in this study. The frequency of chimera bud inducement reached 6.33% when incised part was treated with 2.0 mg/L 6-BA +1.0 mg/L NAA. (2) The chimeras showed resemblances and differences in leaf style, leaf shape, leaf color, flower shape, flower color, flower initiation, tuber swelling, TuMV resistance when compared with their parents. (3) Leaf structure of chimeras appeared chimerical characteristics compared with their parents. Most cells of periclinal chimera leaves were from cabbages in FCW detection, while there was no significant difference in cell numbers of merclinal chimera from cabbage and tuber mustard. Chromosome number of cabbage (2n=18) was found as well as tuber mustard (2n=36) in root-tips of the same plant. Meanwhile, there were many cells contained different chromosome number from its parents, among which some were less than 2n=18 and some were more than 2n=36. |
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