Phenazine‐1‐carboxylic acid and soil moisture influence biofilm development and turnover of rhizobacterial biomass on wheat root surfaces

Journal Article · 25 July 2018 · Environmental Microbiology

DOI: https://doi.org/10.1111/1462-2920.14244 · OSTI ID:1461899

LeTourneau, Melissa K. ^[1]; Marshall, Matthew J.  ^[2]; Cliff, John B. ^[3]; Bonsall, Robert F. ^[4]; Dohnalkova, Alice C. ^[3]; Mavrodi, Dmitri V.  ^[5]; Devi, S. Indira ^[6]; Mavrodi, Olga V. ^[5]; Harsh, James B. ^[1]; Weller, David M. ^[7]; Thomashow, Linda S.  ^[7]

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1. Department of Crop &, Soil Sciences Washington State University Pullman WA 99164‐6420 USA
2. Earth &, Biological Sciences Directorate Pacific Northwest National Laboratory Richland WA 99352 USA
3. Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory Richland WA 99352 USA
4. Department of Plant Pathology Washington State University Pullman WA 99164‐6420 USA
5. Department of Biological Sciences University of Southern Mississippi Hattiesburg MS 39406‐0001 USA
6. Institute of Bioresources and Sustainable Development Takyelpat Manipur Imphal 795001 India
7. United States Department of Agriculture – Agricultural Research Service Wheat Health, Genetics, and Quality Research Unit Pullman WA 99164‐6430 USA

Summary Phenazine‐1‐carboxylic acid (PCA) is produced by rhizobacteria in dryland but not in irrigated wheat fields of the Pacific Northwest, USA. PCA promotes biofilm development in bacterial cultures and bacterial colonization of wheat rhizospheres. However, its impact upon biofilm development has not been demonstrated in the rhizosphere, where biofilms influence terrestrial carbon and nitrogen cycles with ramifications for crop and soil health. Furthermore, the relationships between soil moisture and the rates of PCA biosynthesis and degradation have not been established. In this study, expression of PCA biosynthesis genes was upregulated relative to background transcription, and persistence of PCA was slightly decreased in dryland relative to irrigated wheat rhizospheres. Biofilms in dryland rhizospheres inoculated with the PCA‐producing (PCA ⁺ ) strain Pseudomonas synxantha 2‐79RN ₁₀ were more robust than those in rhizospheres inoculated with an isogenic PCA‐deficient (PCA ^‐ ) mutant strain. This trend was reversed in irrigated rhizospheres. In dryland PCA ⁺ rhizospheres, the turnover of ¹⁵ N‐labelled rhizobacterial biomass was slower than in the PCA ^‐ and irrigated PCA ⁺ treatments, and incorporation of bacterial ¹⁵ N into root cell walls was observed in multiple treatments. These results indicate that PCA promotes biofilm development in dryland rhizospheres, and likely influences crop nutrition and soil health in dryland wheat fields.

• Sponsoring Organization: USDOE
• Grant/Contract Number: SC0014664; AC05-76RL01830
• OSTI ID: 1461899
• Alternate ID(s): OSTI ID: 1468485
• Journal Information: Environmental Microbiology, Journal Name: Environmental Microbiology Journal Issue: 6 Vol. 20; ISSN 1462-2912
• Publisher: Wiley-BlackwellCopyright Statement
• Country of Publication: United Kingdom
• Language: English