Abstract:

This study aims to label the biocontrol agent Burkholderia vietnamiensis B418 with the red fluorescent protein DsRed and investigate the functional stability of the labeled strain. The recombinant plasmid pGEX-4T-1-DsRed containing the DsRed gene was transformed into B418 by the aminoclay-mediated transformation system. Germicul ture, subculture, and dual-culture techniques were used to determine the functional stability of the labeled strain B418-Ds Red.The growth curve and morphological characteristics of the strain B418-DsRed after aminoclay transformation were essentially the same as the wild strain B418. After ten generations of subculturing, bright red fluorescence could still be observed under a confocal microscope and the DsRed gene could be detected by polymerase chain reaction, after plasmid extraction from the strain B418-DsRed, which showed its good genetic stability. Dual-culture confrontation assay revealed that the inhibition rates of the strain B418-DsRed against Fusarium oxysporum and Verticillium dahliae were 55.25% and 67.55%, respectively, with no significant difference when compared to the wild strain B418. It was indicated that the introduction of a foreign plasmid showed no impact on their antifungal activity. Results demonstrated that the red fluorescent protein labeling of the strain B418 was successfully achieved by an aminoclay-mediated transformation system and the labeled strain B418-DsRed with stable function could be used in the future for the colonization of the strain B418 and interaction with pathogens in the plant rhizosphere.

Key words: Burkholderia vietnamiensis, DsRed, aminoclay, functional stability