| Pieris rapae L. and Plutella xylostella L, belong to Lepidoptera, are the main pest disserve Chinese cabbage vegetables. Aiming at the increasing of pest resistance, genetic engineering using insecticidal protein gene were carried out in Chinese cabbage (Brassica campestris L. ssp. pekinensis and B.campestris L.ssp.chinensis ). Meanwhile to assay the safety of the transgenic plants, bar gene transferred to the plants was used as the marker gene to study the foreign gene introgression possibility via pollination in Ccruciferae crops .1. Molecular Breeding of Chinese cabbage for Insect ResistanceThree plant expression plasmids with pinll (proteinase inhibitor II) gene from potato and (or) with sip (spider insecticidal protein) gene from spider were constructed and transformed Agrobacterium tumefaciens. B.campestris ssp.pekinensis was transformed using the leaf disc method, and leaves of the regenerated plants were used to induce shoots again to eradicate the chimerical status. B.campestris ssp chinensis was transformed with the agrobacterium mediated vacuum infiltration method. About 88 independent transgenic lines were obtained. Genetic analysis of the transformants was conducted using bar gene mediated herbicide resistance trait as the marker. The segregation ratios indicated that majority of them accord with Mendelian law, with one or two insertion loci, but some of them did not go along with the physical inserts revealed by genomic Southern blotting, bar, pinll and sip gene could be linked inserted and inherited, but gene exchange or loss could happened in some of the transgenic lines. Bioassay for Pieris rapae L. and Plutella xylostella L resistance showed that larvae fed with transgenic leaf tissue had a higher mortality, and the developments of them were retarded compared with those larvae fed with non-transgenic control plants. In some transgenic lines in B.campestris ssp chinensis, the mortality of Plutella xylostella L reached to 98%, and was 3.8 times higher than the control. Homozygous lines of transgenic B.campestris ssp.pekinensis and B.campestris ssp chinensis were got by microspore culture and repeated self-crossing separately.Researches on the vacuum infiltration techniques revealed that transformational event occurred late in floral development as all the transformants were hemizygous. Transgenic seeds distributed throughout the entire infiltrated plants, and siliques of the upper parts seemed owning more transgenic seeds. Tansformants occurred in all kinds of treated materials no matter the plants with flowering inflorescence or just with inflorescence or just with differentiated flower buds. Factors influencing the growth of the treated plants and seed setting also obviously influenced the transformation frequency, esp. the plant transformation frequency (No. of transformed seeds divided by No.of treated plants).2. Foreign gene introgression as indicated by bar gene via pollination in Cruciferae plants Utilizing the homozygous transgenic Chinese cabbage (B.campestris L.ssp.chinensis) harboringintroduced foreign bar gene, biosafety assay for the foreign gene flow and introgression possibility into other Cruciferae plants via pollination was carried out in the open filed condition and in the greenhouse. It was substantiated by morphological observation, chromosome and DNA identification that the bar gene, conferring the resistance to herbicide basta in transgenic Chinese cabbage (Brassica campestris ssp. chinensis), could intrude into the genomes of turnip (B. campestris ssp.rapifera), heading Chinese cabbage (B. campestris ssp. pekinensis) and other non-heading Chinese cabbage (B. campestris ssp. chinensis ) in a relatively high frequency while into genome of B. napus at a low frequency via natural cross-pollination in open field . Herbicide resistant hybrids of B. nigra, B. carinata, and B. juncea could be gotten at a certain frequency in greenhouse by hand pollination. At no time did the resistant hybrid plants of transgenic Chinese cabbage with B. oleracea, R. sativus...
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