Growing plants on oily, nutrient-poor soil using a native symbiotic fungus

Timothy S Repas; D Michael Gillis; Zakia Boubakir; Xiaohui Bao; Gary J Samuels; Susan G W Kaminskyj

doi:10.1371/journal.pone.0186704

Growing plants on oily, nutrient-poor soil using a native symbiotic fungus

PLoS One. 2017 Oct 19;12(10):e0186704. doi: 10.1371/journal.pone.0186704. eCollection 2017.

Authors

Timothy S Repas^{1

2}, D Michael Gillis¹, Zakia Boubakir¹, Xiaohui Bao¹, Gary J Samuels³, Susan G W Kaminskyj¹

Affiliations

¹ Biology Dept, University of Saskatchewan, Science Place, Saskatoon, SK, Canada.
² Roy Northern Environmental, Fort St John, BC, Canada.
³ USDA-ARS, Systematic Mycology and Microbiology Lab, Beltsville, MD, United States of America.

Abstract

The roots of land plants associate with microbes, including fungal symbionts that can confer abiotic stress tolerance. Bitumen extraction following oil-sand surface mining in the Athabasca region of Alberta, Canada removes plant nutrients but leaves a petrochemical residue, making the coarse tailings (CT) hostile to both plants and microbes. We isolated an endophyte strain of the Ascomycete Trichoderma harzianum we call TSTh20-1 (hereafter, TSTh) from a dandelion that was naturally growing on CT. TSTh colonization allowed tomato, wheat, and remediation seed mixtures to germinate and their seedlings to flourish on CT without the use of fertilizer. Compared to control plants, TSTh increased germination speed, percent germination, and biomass accumulation. TSTh also improved plant water use efficiency and drought recovery. TSTh-colonized plants secreted twice the level of peroxidase into CT as did plants alone. Over two months, plants colonized with TSTh doubled the petrochemical mobilization from CT over plants alone, suggesting a peroxide-mediated mechanism for petrochemical degradation. TSTh grew on autoclaved CT, bitumen, and other petrochemicals as sole carbon sources. Further, TSTh is a micro-aerobe that could metabolize 13C-phenanthrene to 13CO2 in 0.5% oxygen. TSTh has excellent potential for contributing to revegetating and remediating petrochemical contamination.

MeSH terms

Fungi / physiology*
Plant Development*
Soil*
Symbiosis*

Substances

Soil

Grants and funding

We thank the following for support: Natural Sciences and Engineering Research Council (Canada, NSERC DG 203696-13 to SGWK); 'Research Tools and Instruments' (SGWK et al.) for the AxioImager.Z1; Dept Biology (UofS) Biology Graduate Scholarship, NovoZymes BioAg, NSERC IPS (to TSR); NSERC DG and Kaminskyj Research Ltd (to ZB). We thank Marlynn Mireau for the DAB photograph. We thank Roy Northern Environmental for petrochemical-impacted soils and analysis. We greatly thank colleagues who provided plants and samples from CT sites. TSR was an employee of Roy Northern Environmental during the editing of this manuscript. RNE did not play a role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.