The Competitiveness And Effectiveness Of Phaseolus Rhizobia Studied By Using CFP Marker Gene Technique

One nitrogen fixing effective strain was selected out from 20 phaseolus rhizobia strains, which were isolated from the different cultivars and locations in Yunnan and Sichuan, by observing nodule number ,fresh nodule weight,plant height and dried plant weight on three cultivars which were planted popularly in Sichuan by Pot experiment of in experiment in nitrogen-free sand. SC18-cfp strain with cfp gene marker was obtained triumphantly by thri-parental mating. Ten transformants,which named SC18- cfp -1, SC18- cfp -2, SC18-cfp-3, SC18-cfp-4, SC18-cfp-5, SC18-cfp-6, SC18-cfp-7, SC18-cfp-8, SC18-cfp -9 and SC18- cfp -10 were purified and tested for their marker stability. By the pot experiment in nitrogen-free sand, the difference of the parental strain and marked strains with cfp gene on three cultivars was tested. One marked strain which was not significantly different with the parental strain for the competition stady with soil indigenous strains under field conditions.The cfp gene can express in SC18- cfp. After continously transferring one hundred and fifty generations on YEM broth medium and in nodulation process,the characteristic of fluorescent were kept stable. Compared with the parental strain, the growth velocity of SC18- cfp was not changed significantly.In the nitrogen-free Pot experiment, the nodulating competitive ability of the parental and marked strains and their nitrogen fixing efficiency were tested. Co-inoculating parental and marked stains at 1:1 ratio, their competitive ability was tested. The results showed the proportion of fluorescent nodules did not differ significantly from 50%. It indicated thecompetitiveness of marked strain was not changed significantly compared with the parental strains. The results indicated that using the cfp gene marker technique to study the competitive ability of rhizobia was practical.By the experiment of mentioned above, one effective nitrogen fixing strain was selected. Applying the cfp gene marker technique to study the competitive ability of SCI 8- cfp strain, the results indicated that the competitive ability of SCI8- cfp strain was higher than that of the soil indigenous phaseolus rhizobia r. Their nodule occupancy which were compared with the parental strains were reach to prominence. In conclusion, the SCI8 strain was matched with the three cultivars and was a effective nitrogen fixing strain.