An ABC transporter mutation alters root exudation of phytochemicals that provoke an overhaul of natural soil microbiota

Abstract

Root exudates influence the surrounding soil microbial community and recent evidence demonstrates the involvement of ABC transporters in root secretion of phytochemicals. In this study, we examined effects of seven Arabidopsis ABC transporter mutants on the microbial community in native soils. After two generations, only the Arabidopsis abcg30 (Atpdr2) mutant had significantly altered both the fungal and bacterial communities compared with the wild type using automated ribosomal intergenic spacer analysis (ARISA). Similarly, root exudate profiles differed between the mutants; however, the largest variance from the wild type (Col-0) was observed in abcg30, which showed increased phenolics and decreased sugars. In support of this biochemical observation, whole genome expression analyses of abcg30 roots revealed that some genes involved in biosynthesis and transport of secondary metabolites were up-regulated while some sugar transporters were down-regulated compared with genome expression in wild type roots. Microbial taxa associated with Col-0 and abcg30 cultured soils determined by pyrosequencing, revealed that exudates from abcg30 cultivated a microbial community with a relatively greater abundance of potentially beneficial bacteria (i.e. PGPRs, nitrogen fixers) and were specifically enriched in bacteria involved in heavy metal remediation. In summary, this is the first report of a single gene mutation from a functional plant mutant influencing the surrounding community of soil organisms, showing that genes are not only important for intrinsic plant physiology but for the interactions with the surrounding community of organisms.