Improving biocontrol effect ofPseudomonas fluorescensP5 on plant diseases by genetic modification with chitinase gene

Abstract Pseudomonas fluorescensP5 was isolated in Yunnan Province and proved to be an effective biocontrol agent of various soil-borne plant diseases. The aim of the study was to enhance the biocontrol effect of this strain by introducing a chitinase gene. A 6.5 kb DNA fragment containing the chitinase genechiBwas inserted into pDSK519 vector to construct a new plasmid, pDSK51965. This plasmid was introduced intoP. fluorescensP5 and resulted in a new strain named P5-1. Restriction enzyme digestion and chitin plate culture confirmed that P5-1 contained a functional chitinase gene. Compared with wild-type P5 in pot experiments, P5-1 had an increased effect against rice sheath blight and cotton damping-off caused byRhizoctonia solani. It also increased the effect on suppression of wheat take-all caused byGaeumannomyces graminisvar.tritici.