Abstract:The vector pGFP containing PP303 promoter was constructed. Then plasmid pJBA28 and pGFP were transformed into E.coli S17-1/λπ respectively, and sequently the conjugation was carried on. S17-1/λπ (pJBA28) and S17-1/λπ (pGFP) were donor strains, and P303 was recipient strain. The conjugants P303m1 and P303m3 which fluoresced steadily under 488nm were acquired. Both PCR and Southern blotting analysis demonstrated that gfp gene had been inserted into P303 chromosomal DNA randomly. SDS-PAGE assay indicated that the expression of GFP in P303m3 (carried PA1/04/03) was weaker than in P303m1 (carried PP303), and the expression of gfp gene located in the chromosome was weaker than in the shuttle plasmid. The growth curve of P303m1 certified that it was the same growth speed as the wild strain P303. Genetic stability result showed that the stability of gfp gene remained 100% after 96 h. P303m1 remained strong antifungal activity against seven kinds of plant pathogenic fungi as P303. The survival and colonization of P303 and P303m1 were investigated by selective culture and PCR identified methods. The results showed that the ability of colonization of P303 and P303m1 in the soil and rhizos- phere was much stronger than that around phyllosphere. The total population of P303 and P303m1 were 1.63×104 and 3.30×102 cfu/g soil (wet weight) in the 60 days after incubation in natural soil, and 3.29×106 and 4.1×104 cfu/g roots (wet weight) in the 60 days in the rhizosphere of cabbage respectively.