Biological Control of Fungal Plant Pathogens: Stable Inheritance of Heterologous Antibiotic Biosynthesis Genes in a Root-Colonizing Pseudomonad

摘要

Researchers proposed to introduce a region of the chromosome of the growth-promoting rhizobacterium Pseudomonas fluorescens strain NZ130, shown to be involved in the production of a ferric antagonized inhibitor (FAI), into the root-colonizing P. putida strain MK280. By using either a newly developed plasmid cloning vector, pVSP41, or by chromosomal integration, they hoped to ensure stable inheritance of the introduced genes. When cloned into pVSP41, and introduced into MK280, an antifungal phenotype was observed in vitro. Unfortunately, the recombinant plasmids were unstable in the new host due to apparent toxicity of the products encoded by the heterologous FAI genes. Chromosomal cointegration led to stable inheritance of the NZ130 FAI genes, but expression of the antifungal phenotype was not observed. Comparative studies of RNA levels between the recombinant strains and NZ130 indicated that the cloned region may not encode all the genes necessary for efficient production of FAI in MK280.