Agrobacterium-mediated Transformation In Citrus And The Resistance Analysis Of The Transgenic Plants

Citrus bacterial canker disease (CBCD) is a quarantine disease in the world, which restricts the development of citrus industry seriously. One of the important way to solve canker diease is to create new resistant species. This research transformed pthA gene and Xa27gene into susceptible lemon (C. Lemon L.) and obtained transgenic plants. Identified the transgenic plants and inoculated with Xac on the positive lines. The main results were as follows.1. Using agrobacterium-mediated transformation, pthA gene was trandformed into about500lemon stems.57transgenic plants were identified and45of them were positive lines, the positive rate was78.9%. Xa27gene was trandformed into about1000lemon stems.29transgenic plants were identified and10of them were positive lines, the positive rate was34.5%.2. According to the gene expression analysis, chose pthA lemon#7,#22and#23to do the inoculation test. The wild type and transgenic lines all showed canker disease phenotype at4DAI, but the morbidity of wild type was100%, the disease point rate was86%. The transgenic lines#7and#23also had100%morbidity, but the disease point rate were72%and47%respectively, lower than the wild type. What’s more, the lesion size of wild type was bigger than#7and#23. As for the transgenic lines#22, the morbidity was75%, disease point rate was33%, lesion size was0.028cm2, these three aspects were all lower than the wild type. And the DI of three transgenic lines were also lower than the wild type. The results showed that the transgenic plants enhanced the resistance to citrus canker.3. Chose Xa27lemon#5and#25to do the inoculation test. At4DAI, the morbidity of transgenic lines were50%and33.3%respectively, the disease point rate were14%and40%, the lesion size were0.019cm2and0.012cm2, and DI was16and5. These four aspects were all lower than the wild type, indicated that the Xa27lemon enhanced the resistance to citrus canker.