Cabbage Conversion Method And Mechanism To Explore

Chinese cabbage,the most important economic crop,its cultivation needs a large amount of water but drought breeding resources is in shortage in our country.Introducing foreign gene into Chinese cabbage through genetic engineering may create novel germplasms with drought tolerance.In this study,BADH(encoding betaine aldehyde dehydrogenase) and CMO(encoding choline monoxygenase),both for osmostic regulation and KT383(encoding transcription regulation factors) were used to be transformed into several homozygous and heterozygous Chinese cabbage with Agrobacterium-mediated in vitro and in planta transformation.30 times transformations were conducted in order to transfer BADH into 'Beijing 80' by Agrobacterium-mediated in vitro transformation.Although 20 kanamycin resistant plants were got,none was found to be positive by polymerase chain reaction(PCR) analysis.'Floral dip' were carried out 3 times on 6 cultivars from advanced lines '3-833,07-806,7-859,07-696,07-1000,07-544' and the Pakchoi variation '49caixin' using Agrobacterium carrying different genes:BADH,CMO and KT383.However, none resistant plants were obtained by selection of kanamycin and glyphosate.The processes during shoot regeneration and Agrobacteria distribution were observed in explants(cotyledon with petiole) by means of paraffin section.The results revealed that the shoot from infected and uninfected explants were both derived from multiple meristematic nodules formed by vascular bundles at the petiolar end.The time of shoot regeneration was delayed in infected explants compared with uninfected ones.Agrobacteria were widespread in cortex cells,vascular bundles,formed meristematic nodules and cotyledons,by which the survival and movement of Agrobacteria during co-culture can be confirmed.After one week culture on shoot inducing and selection medium,Agrobacteria in petiolar end of albinism or browning explants were in high density,which imply negative relation between Agrobacteria concentration and survival of plant cells.Although successful in planta transformation had been reported on Crucifer plants such as Arabidopsis,49caixin,Brasscia napus,the method wasn't applied on Chinese cabbage until now,so it was a challenging work.Histochemical assays of paraffin sections revealed that when flower buds were about 0.15mm,0.5mm,0.5mm in diameter for Arabidopsis,49caixin,Brasscia napus respectively,the ovarys were open.A case study of open ovary,the percent of flower buds with open carpels in inflorescence are 20%,12.9%,11.7%and 10%for Arabidopsis,Brasscia napus, Chinese cabbage and 49caixin,respectively.By combining diameter,development stages,location of flower buds and their correlation,time taken for the flower buds with unopened carples to bloom was about 15d,13d,10d and 3d for 49caixin, Chinese cabbage,Brassica napus and Arabidopsis,respectively.These results showed the differences of flower development among Crueiferae plants and may offer some factors affecting frequency of in planta transformation.