Improvement Of Insect-resistance And Disease-resistance Of Chinese Cabbage By Genetic Engineering

Chinese cabbage is an important vegetable which it is popular in China because its rich nutrition, high yield, low price and easy to store. Chinese cabbage breeding in the Intitute of Vegetables, Shanxi Academy of Agricultural Science stands frontrank in China, Chinese cabbage seeds produced by this institute can make at least 3 million RMB. Recent years, Chinese cabbage severely suffers soft-rot disease and insects damage because of pollution of environment and greenhouse effect. Misuse of chemicals can control the disease and the insects to some extent, which leads to the pollution of environment and the damage of people's health. Now disease-resistant and insect resistant Chinese cabbage breeding becoming pressing because it is gradually restricted by lacking of suitable breeding materials. It become more important to breeding by combination of traditional breeding and biotechnology. Selection of new variety of insect-resistance and disease-resistance will be a trend to agricultural development in future, genetic engineering breeding has the advantages of strong selection and security and cheap and effectiveness, it has also consecutiveness and comprehensive to plant protection comparing traditional protection of insect and disease.Highly-effectiveness and stabilization of genetic transformation system are premises of obtaining transgenic Chinese cabbage. In this study, we used 8 parental lines of Chinese cabbage which are generalized at present in china, and selected 5 lines which were easy to regeneration, we also established two transgenic systems - cotyledonary regeneration systemfrom sterile seedlings, and optimized the various conditions including different hormone and combination, different additives, different genotypes, different age of seedling, different types of explants, preculture, concentration of bacteria, infection times, coculture, concentration of carbinicilin, concentration of kanamycin and phenol chemicals. A highly-effective and stabilized transgenic system was established. The order of regeneration frequency of Chinese cabbage is Qingmaye C, Qingmaye D, Hetouzao A, Hetouzao B, Shite 11-3 from high to low.We transformed the cowpea trypsin inhibitor gene and anti-bacterium peptide gene into the 5 Chinese cabbage lines using agrobacterium-mediated method. Transgenic plants were obtained from two kinds of regeneration systems. The regenerated plants have been demonstrated by PCR, Southern blotting that ex-genes of insect-resistance and disease-resistance have been inserted into plants, although transgenic frequency is different. The tests of Northern blotting were indicated that transcription of two ex-genes had been transcribed normally;The experiments in the field demonstrated that ex-genes have given the traits of insect-resistance and disease-resistance. It is also found that the abilities of insect-resistance and disease-resistance is different in different transgenic plants, ex-genes could not been verified in some transgenic plants, also, some transgenic plants did not express the traits of insect-resistance and disease-resistance even if ex-genes could been verified, which indicated that gene silencing happened in these transgenic plants.The tests have demonstrated that Chinese cabbage acquired the insect-resistant and the disease-resistant traits. The experiments by feed insects showed that SCK transgenic plants have stronger insect-resistance at earlier stage. Disease-resistance of transgenic plants have also similarphenomenon. Different transgenic varieties and different transgenic plants from one ex-gene have wide differences in the insect-resistance and the disease-resistance.Ti generation had been acquired by self-cross in the 5 transgenic Chinese cabbage parental lines. The experiments showed that the kanamycin-resistant segaregation ratio of 4 varieties of Ti generationplants fit for 3 ! 1 except Hetouzao B.