Title : Relationship between plant gene expression and microbial community diversity in remediation of acidic metalliferous mine tailings using compost amendment
Abstract:
Successful phytoremediation of acidic metal-contaminated mine tailings requires amendments to condition tailing properties prior to plant establishment. This conditioning process is complex and includes multiple changes in tailings properties. Particularly, little is known about the plant genetic response during remediation, or how this response influences soil microbial diversity (and vice versa). The objective of this project was to identify relationships between tailing properties and plant stress response genes during growth of Atriplex lentiformis in compost-amended (10%, 15%, 20% w/w) mine tailings. Analyses included RNA-seq of plant root-gene expression, 16S rRNA gene amplicon sequencing for bacterial/archaeal communities, metal concentrations in substrate and plant tissues, and phenotypic responses of plants to stress. Differences in plant stress gene expression and microbial diversity were observed as a function of compost amendment. For example, the expression of root-associated plant stress genes and the abundance of acidophilic microbes (e.g., Fe/S, and S oxidizers) were highest in the 10% compost treatment. As compost levels increased, plant stress genes were down-regulated and microbial richness increased as did the presence of plant-growth-promoting bacteria and N2-fixers. Importantly, the expression of plant stress genes had strong positive correlations with abundant microbial taxa at each compost level. Results suggest there are strong plant-microbiome associations that drive the success or failure of the revegetation process. Such data are essential for development of better remediation management strategies for metal-contaminated sites.
