PERSISTENCE IN SOIL OF THE PLANT-GROWTH PROMOTING RHIZOBACTERIUM PSEUDOMONAS-PUTIDA GR12-2 AND GENETICALLY MANIPULATED DERIVED STRAINS

Transformation of the plant growth promoting rhizobacterium Pseudomona s putida GR12-2 with broad-host-range vectors can affect the growth of the bacterium, its ability to promote root elongation of canola seedl ings under gnotobiotic conditions, and its persistence in soil. Plasmi d transformants, and a transposon-mutagenized derivative of P. putida GR 12-2, fell into two classes with respect to these three attributes: strains that were clearly diminished in these capabilities and strain s that behaved like the nontransformed wild type. These differences ca n be accounted for by the imposition of a metabolic load that is creat ed by some types of genetic modification that results in a physiologic al impairment of the modified bacterium and decreases its ability to f unction as a plant growth promoting rhizobacterium.