Toxic metal tolerance of Arabidopsis arenosa inoculated with fungal endophyte Mucor sp. Gene expression study. Arabidopsis arenosa

To determine the mechanisms of improved toxic metal tolerance of A. arenosa inoculated with Mucor sp. whole gemone microarray profiling was employed. Metal toxicity altered the expression of 5169 probe sets; 2861 genes were up-regulated and 2308 down-regulated. Inoculation with the fungi induced changes in the expression of 899 probes from the above presented data set; 492 genes were up-regulated and 314 were down-regulated. The expression of 93 genes (63 and 30, up and down-regulated respectively) was affected by both treatments (Fig. 5A-B). Genes differentially expressed in E+ plants vs E- from mine dump substrate were subject to GO analysis (gene ontology) to identify enriched terms with a cut-off rate of 0.01. The majority of the genes upregulated belonged to ROS metabolism, response to biotic and abiotic stimuli, response to ion starvation and ET biosynthesis and signaling functional categories. Among down-regulated transcripts GO analysis revealed a significant enrichment in the regulation of anthocyanin biosynthesis term. Overall design: Gene expression profiles of roots of A. arenosa inoculated at 2 leaf seedling stage (10 days after germination), grown in substrate from the “Bolesław”(Poland, (50°16'58"N 19°32'9"E) mine dump, polluted with Zn, Cd, Fe and Pb, not inoculated grown in the same substrate and plants not inoculated grown in commercially available soil were compared. In order to distinguish between the effect of fungi colonization and toxic metal stress on the plants transcriptome, we compared global gene expression of E- plants cultivated in control substrate (commercially available soil mixed with sand in a 2:1 v:v ratio) with E- A. arenosa grown in substrate from the mine dump. Subsequently, the obtained data set was compared to the gene expression profile of Mucor sp. inoculated plants grown in the toxic metal enriched environment (mine dump substrate).