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

Authors: ZHANG, JIBIN - Huazhong Agricultural University; YANG, MINGMING - Northwest A&f University; MAVRODI, DIMITRI - University Of Southern Mississippi; Kelton, Jason; Thomashow, Linda; Weller, David

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2020
Publication Date: 3/24/2020
Citation: Zhang, J., Yang, M., Mavrodi, D.V., Kelton, J., Thomashow, L.S., Weller, D.M. 2020. Pseudomonas synxantha 2-79 transformed with pyrrolnitrin biosynthesis genes has improved biocontrol activity against soilborne diseases of wheat and canola. Phytopathology. 110: 1010-1017. https://doi.org/10.1094/PHYTO-09-19-0367-R.
DOI: https://doi.org/10.1094/PHYTO-09-19-0367-R

Interpretive Summary: Soilborne pathogen that cause root diseases are major production-limiting factors in cereal-based production systems of the Pacific Northwest where wheat, barley, canola, chickpeas, pea and lentils are grown. Biocontrol Pseudomonas bacteria produce natural antibiotics that contribute to the ability of these bacteria to suppress soilborne plant pathogens of these crops. However, these Pseudomonas biocontrol agents often suppress only a single soilborne pathogen, yet multiple pathogens often attack a crop simultaneously. Pseudomonas strain 2-79 is highly effective as a seed treatment against the root disease of wheat known as take-all. In order to improve the spectrum of biocontrol activity against other root diseases, genes encoding the biosynthesis of another antibiotic were inserted into strain 2-79. The recombinant strain suppressed a much broader number of diseases as compared to the parental strain 2-79. Thus, genetic engineering offers an approach to both improve the efficacy of a biocontrol agent and to broaden the range of diseases an agent can control.

Technical Abstract: 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. 'uorescens) 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 R. solani AG-8 and AG-2-1, Gaeumannomyces graminis var. tritici, Sclereotinia sclerotiorum, Fusaruim culmorum, and F. pseudograminearum significantly more than the strain 2-79. Both 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 the wild-type strain 2-79.