Pseudomonas synxantha 2-79 transformed with pyrrolnitrin biosynthesis genes has improved biocontrol activity against soilborne pathogens of wheat and canola.


Huazhong Agricultural University, 47895, State Key Laboratory of Agricultural Microbiology, Wuhan, Hubei , China; [Email]


A four-gene operon (prnABCD) from Pseudomonas protegens Pf-5 encoding the biosynthesis of the antibiotic pyrronitrin (Prn) was introduced into P. synxantha (formerly P. fluorescens) 2-79, an aggressive root colonizer of both dryland and irrigated wheat roots that naturally produces the antibiotic phenazine-1-carboxylic acid (PCA) and suppresses both take-all and Rhizoctonia root rot of wheat. Recombinant strains ZHW15 and ZHW25 produced both antibiotics and maintained population sizes in the rhizosphere of wheat that were comparable to those of strain 2-79. The recombinant strains inhibited in vitro the wheat pathogens Rhizoctonia solani AG-8 and AG-2-1, Gaeumannomyces graminis var. tritici, Sclereotinia sclerotiorum, Fusaruim culmorum, and F. pseudograminearum significantly more than did strain 2-79. Both the wild-type and recombinant strains were equally inhibitory of Pythium ultimum. When applied as a seed treatment the recombinant strains suppressed take-all, Rhizoctonia root rot of wheat and Rhizoctonia root and stem rot of canola significantly better than did wild-type strain 2-79.

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