Study On Rice Tissue-specific Promoter And Recombination Efficiency Of CinH,ParA

With the development of biotechnologies,especially the recombinant DNA technology,crops transgenic technology has entered a period of rapid development.The advantages of genetically modified(GM)crops in insect control,herbicide resistance,stress tolerance,etc has been gradually revealed.However,food safety and environmental safety of GM crops have been manifested.The safety of transgenes,especially selectable marker genes,has become a key part of the researchers' study.Many resaerchers use non-toxic selecable marker genes or remove selecable marker genes to improve the safety of transgenic plants.Selectable marker gene removal technologies include transposon-mediated marker gene deletion,co-transformation for selectable marker gene deletion and site-specific recombination system mediated selectable marker gene deletion.In addition to selectable marker gene removal,the transgene deletion technology is another way to improve the safety of genetically modified crops.The utilization of the site-specific recombination system is a key to remove transgenes.We can use tissue-specific promoters to express recombinase genes in specific tissue and these recombinases can catalyze recombination reaction in specific tissue.This thesis mainly focuses on tissue-specific promoters and the recombination efficiency.By screening in the rice gene expression database,we found five promoters of interest.I used these promoters to control the expression of recombinase C inH via connecting the cin H gene and these promoters in b inary vectors.After that,we transformed the b inary vectors to rice callus.When I got regeneration rice plants,I extracted the RNA from the rice seeds and leaves to measure the cin H gene expression in seeds and leaves.Finally,I found that promoters of LOC_Os07g11510,LOC_Os02g15090 and LOC_Os07g11650 genes could express CinH specificly in rice seeds.I also tested the recombination efficiency between single copy and muticopies recombination site RS2 or MRS via in vitro recombination reaction.I found that single copy RS2 or MRS could recombine more easily than muticopies when recombination sites RS2 or MRS were in circular plasmids.However,when recombination sites RS2 or MRS were in linear DNA,CinH or ParA could not catalyze recombination reactions.This showed RS2 and MRS recombination reaction need DNA to form higher order structures.