Mycorrhizae and Rhizobacteria on Precambrian Rocky Gold Mine Tailings: I. Mine-Adapted Symbionts Promote White Spruce Health and Growth.

Martin B Nadeau,Damase P Khasa,Joan Laur

doi:10.3389/fpls.2018.01267

Martin B Nadeau, Damase P Khasa + Show 1 more

Open Access

https://doi.org/10.3389/fpls.2018.01267

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Abstract

White spruce [Picea glauca (Moench) Voss] is a commercially valuable boreal tree that has been known for its ability to colonize deglaciated rock tailings. Over the last decade, there has been an increasing interest in using this species for the revegetation and successful restoration of abandoned mine spoils. Herein, we conducted a glasshouse experiment to screen mycorrhizal fungi and rhizobacteria capable of improving the health and growth of white spruce seedlings growing directly on waste rocks (WRs) or fine tailings (FTs) from the Sigma-Lamaque gold mine located in the Canadian Abitibi region. After 32 weeks, measurements of health, growth, and mycorrhizal colonization variables of seedlings were performed. Overall, symbionts isolated from roots of healthy white spruce seedlings growing on the mining site, especially Cadophora finlandia Cad. fin. MBN0213 GenBank No. KC840625 and Pseudomonas putida MBN0213 GenBank No. AY391278, were more efficient in enhancing seedling health and growth than allochthonous species and constitute promising microbial symbionts. In general, mycorrhizae promoted plant health and belowground development, while rhizobacteria enhanced aboveground plant biomass. The observed beneficial effects were substrate-, strain-, and/or strains combination-specific. Therefore, preliminary experiments in control conditions such as the one described here can be part of an efficient and integrated strategy to select ecologically well-adapted symbiotic microorganisms, critical for the success of a long-term revegetation program.

Highlights

Mining operations generate an enormous volume of waste materials that are difficult to dispose of
In the context of evaluating a new selection strategy for site-specific reforestation, we investigated the potential of selected cultivable fungi and rhizobacteria to improve the performance of white spruce seedling on mine tailings under glasshouse conditions
The proportion of healthy green foliage on seedlings inoculated with C. finlandia and T. scalpturatum was significantly greater than control plants without fungal inoculation (Figure 2C, left panel; P-value < 0.0001)

Summary

Introduction

Mining operations generate an enormous volume of waste materials that are difficult to dispose of. A few healthy white spruce [Picea glauca (Moench) Voss] seedlings found naturally regenerating on the mine tailings revealed a mycorrhizal fungal community distinct from the neighboring ecosystems (Nadeau et al, 2016). Beneficial microorganisms discovered from the rhizosphere of seedlings can significantly ease plant growth and development – a major asset in a nutrient-depleted substrate like the Sigma-Lamaque gold mine tailings (Nguyen et al, 2006; Hoeksema et al, 2010). In tailings of a copper mine, fungal inoculation enhanced Japanese red pine (Pinus densiflora) seedlings performance (Zong et al, 2015). In western Canada, Onwuchekwa et al (2014) have shown that the inoculation of white spruce and jack pine (Pinus banksiana) with several fungal species (Hebeloma crustuliniforme, Suillus tomentosus, Laccaria bicolor) improved plant survival on oil sand tailings

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