Virus Resistance Mediated By The CDNAs Encoding For The Movement And Coat Proteins Of Potato Virus X

Transgenic plants expressing virus genes or sequences have been shownto be resistant to plant virus infections. This form of resistance is known aspathogen-derived resistance (PDR). There are several PDR strategies such ascoat, movement and replicase protein genes. In 1993 Lindbo et al have alsofound RNA mediated virus resistance. Due to its advantage of high bio-safetyand effect, the RNA mediated virus resistance has become a hot spot in thearea of plant anti-virus genetic engineering. PVX is the typical member ofPVX genus. Frequently, it coinfects with other plant viruses and decreasesthe output of potatoes enormously. At present, there has been little report onRNA-mediated resistance against PVX. In fact, RNA mediated virusresistance belongs to posttranscriptional gene silencing (PTGS). 25KDmovement protein is a virus suppressor of PTGS. We here describe thetransformation of tobacco with the non-translatable PVX-p25 to generateRNA mediated resistant transgenic tobacco plants by suppressing the virussuppressor. Meanwhile, we also transformed the NC89 with non-translatablePVX-CP. Comparing the difference of virus resistance between them, we canselect more effective gene to transform plants and obtain high resistance ratioof resistant transgenic plants. The main results presented in this thesis are asfollows:1. The non-translatable 25KD MP and the non-translatable CP gene were cloned and inserted between the 35S promoter and nos terminator sequences of the binary vector pROKâ…¡2. The two recombinant plasmids (pROKII-p25 and pROKII-CP) were transferred into Agrobacterium tumefaciens LBA4404 by direct transferring method. PCR and double digestions also confirmed that all the target genes were transferred into Agrobacterium tumefaciens.3. The transformed tissues were selected in the presence of Kanamycin, and the regenerated plants were screened by PCR.