Interplay between plant selenium hyperaccumulation and the bacterial rhizobiome
A. COCHRAN (1), J. Bauer (2), P. Lovecka (3), M. Sura de Jong (3), E. Pilon-Smits (1) (1) Department of Biology, Colorado State University, U.S.A.; (2) Department of Biology, Colorado State University, U.S.A.; (3) Department of Biochemistry and Microbiology, Institute of Chemical Technology, Czech Republic

Here, we combine the use of Illumina sequencing with Se tolerance tests on individual isolates in order to obtain a bigger picture of the rhizobiome of Selenium (Se) hyperaccumulator (HA) plants. Rhizosphere soil samples were taken from a variety of HA and non-HAs from a seleniferous and a non-seleniferous site. An analysis of the 16S rRNA microbial sequences found that there is clearly a difference between the microbiomes of the seleniferous site and the non-seleniferous site. Hundreds of bacteria were isolated from these soil samples and cultured on LB with varying concentrations of selenate and selenite (0-200mM). Most isolates showed extreme resistance to both forms of Se, many with growth unaffected or even enhanced at 200mM selenate. A Kruskal-Wallis test showed no significant differences in Se resistance between soils of origin or host plants of the isolates, indicating that bacterial Se resistance is a constitutive trait that strains living in seleniferous habitats have no need to evolve. Selected isolates from the different soils and hosts were identified using MALDI and inoculated as consortia to Brassica juncea seeds. The inoculated and uninoculated plants were grown with or without 20μM selenate and analyzed for growth and Se accumulation. This Se treatment had a toxic effect on B. juncea growth that was alleviated by inoculation with the consortium of microbes originating from Se HAs from the seleniferous site with no relation to a difference in Se.

Abstract Number: P4-91
Session Type: Poster