Skip to main content
ARS Home » Pacific West Area » Pullman, Washington » WHGQ » Research » Publications at this Location » Publication #376619
Research Project: Biology, Ecology, and Genomics of Pathogenic and Beneficial Microorganisms of Wheat, Barley, and Biofuel Brassicas

Location: Wheat Health, Genetics, and Quality Research

Title: Evaluation of the phytotoxicity of 2,4-Diacetylphloroglucinol and Pseudomonas brassicacearum Q8r1-96 on different wheat cultivars

Author
item YANG, MINGMING - Northwest A&f University
item Thomashow, Linda
item Weller, David

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2021
Publication Date: 4/20/2021
Citation: Yang, M., Thomashow, L.S., Weller, D.M. 2021. Evaluation of the phytotoxicity of 2,4-Diacetylphloroglucinol and Pseudomonas brassicacearum Q8r1-96 on different wheat cultivars. Phytopathology. https://doi.org/10.1094/phyto-07-20-0315-R.
DOI: https://doi.org/10.1094/phyto-07-20-0315-R

Interpretive Summary: Pseudomonas brassicacearum Q8r1-96 and bacteria of the genus Pseudomonas that produce the antibiotic 2,4-diacetylphloroglucinol (DAPG) possess both biocontrol and growth-promoting properties and play an important role in the control of the disease of wheat called take-all in the Pacific Northwest of the United States. However at higher doses, the bacteria can reduce seed germination and cause root necrosis on some wheat cultivars. In this study, we evaluated the effects of strain Q8r1-96 and of DAPG on the germination of 69 wheat cultivars that have been or currently are grown in the Pacific Northwest. The cultivars varied widely in their ability to tolerate the bacteria or DAPG. The frequency of germination of the cultivars ranged from 0 to 0.87 and from 0.47 to 0.90 when treated with Q8r1-96 and DAPG, respectively. Seed germination assays in vitro and in the greenhouse showed significant correlations, especially for spring wheats. In contrast, the effect of Q8r1-96 on seed germination was only weakly correlated with that of DAPG alone, suggesting that other factors contribute to the toxicity of P. Q8r1-96 to wheat. Three wheat cultivars with the greatest tolerance and three cultivars with the least tolerance to Q8r1-96 were tested for their ability to support root colonization by the bacteria. The cultivars with the greatest tolerance supported significantly greater populations of strain Q8r1-96 than those with the least tolerance to the bacteria. Our results show that wheat cultivars differ widely in their interaction with strain Q8r1-96 and the important biocontrol antibiotic DAPG.

Technical Abstract: Pseudomonas brassicacearum Q8r1-96 and other 2,4-diacetylphloroglucinol (DAPG)-producing fluorescent pseudomonads of the P. fluorescens complex possess both biocontrol and growth-promoting properties and play an important role in take-all decline of wheat in the Pacific Northwest of the United States. However at higher doses, P. brassicacearum can reduce seed germination and cause root necrosis on some wheat cultivars. In this study, we evaluated the effects of Q8r1-96 and of DAPG on the germination of 69 wheat cultivars that have been or currently are grown in the Pacific Northwest. The cultivars varied widely in their ability to tolerate P. brassicacearum or DAPG. The frequency of germination of the cultivars ranged from 0 to 0.87 and from 0.47 to 0.90 when treated with Q8r1-96 and DAPG, respectively. Seed germination assays in vitro and in the greenhouse showed significant correlations, especially for spring wheats. In contrast, the effect of Q8r1-96 on seed germination was only weakly correlated with that of DAPG alone, suggesting that DAPG is not the only factor responsible for phytotoxicity of P. brassicacearum Q8r1-96. Three wheat cultivars with the greatest tolerance and three cultivars with the least tolerance to Q8r1-96 were tested for their ability to support root colonization by strain Q8r1-96. The cultivars with the greatest tolerance supported significantly greater populations of strain Q8r1-96 than those with the least tolerance to the bacteria. Our results show that wheat cultivars differ widely in their interaction with P. brassicacearum Q8r1-96 and the important biocontrol antibiotic DAPG.