Project description:Plants are naturally associated with diverse microbial communities, which play significant roles in plant performance, such as growth promotion or fending off pathogens. The roots of Alkanna tinctoria L. are rich in naphthoquinones, particularly the medicinally used chiral compounds alkannin, shikonin and their derivatives. Former studies already have shown that microorganisms may modulate plant metabolism. To further investigate the potential interaction between A. tinctoria and associated microorganisms we performed a greenhouse experiment, in which A. tinctoria plants were grown in the presence of three distinct soil microbiomes. At four defined plant developmental stages we made an in-depth assessment of bacterial and fungal root-associated microbiomes as well as all primary and secondary metabolites. Our results showed that the plant developmental stage was the most important driver influencing the plant metabolite content, revealing peak contents of alkannin/shikonin at the fruiting stage. In contrast, the soil microbiome had the biggest impact on the plant root microbiome. Correlation analyses performed on the measured metabolite content and the abundance of individual bacterial and fungal taxa suggested a dynamic, at times positive or negative relationship between root-associated microorganisms and root metabolism. In particular, the bacterial Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium group and the fungal species Penicillium jensenii were found to be positively correlated with higher content of alkannins.
2021-11-28 | ST002021 | MetabolomicsWorkbench
Project description:Studies of root-associated microbiomes in Gymnadenia conopsea
Project description:Root exudates contain specialised metabolites that affect the plant’s root microbiome. How host-specific microbes cope with these bioactive compounds, and how this ability shapes root microbiomes, remains largely unknown. We investigated how maize root bacteria metabolise benzoxazinoids, the main specialised metabolites of maize. Diverse and abundant bacteria metabolised the major compound in the maize rhizosphere MBOA and formed AMPO. AMPO forming bacteria are enriched in the rhizosphere of benzoxazinoid-producing maize and can use MBOA as carbon source. We identified a novel gene cluster associated with AMPO formation in microbacteria. The first gene in this cluster, bxdA encodes a lactonase that converts MBOA to AMPO in vitro. A deletion mutant of the homologous bxdA genes in the genus Sphingobium, does not form AMPO nor is it able to use MBOA as a carbon source. BxdA was identified in different genera of maize root bacteria. Here we show that plant-specialised metabolites select for metabolisation-competent root bacteria. BxdA represents a novel benzoxazinoid metabolisation gene whose carriers successfully colonize the maize rhizosphere and thereby shape the plant’s chemical environmental footprint
