Journal Article

The lactonase BxdA mediates metabolic specialisation of maize root bacteria to benzoxazinoids

Knoch, Eva, Becker, Claude, Florean, Matilde, Mateo, Pierre, Schandry, Niklas, Pestalozzi, Christine, Bruggmann, Rémy, Schlaeppi, Klaus, Kreuzer, Marco, Wei, Anlun, Erb, Matthias, Giroud, Caitlin, Köllner, Tobias G., Rouyer, Liza, Hapfelmeier, Siegfried, Robert, Christelle A. M., Thoenen, Lisa, Gfeller, Valentin, Notter, Matheus D., Züst, Tobias

2024

Overview

Root exudates contain specialised metabolites that shape the plant’s root microbiome. How host-specific microbes cope with these bioactive compounds, and how this ability affects 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 (6-methoxybenzoxazolin-2(3H)-one) and formed AMPO (2-amino-7-methoxy-phenoxazin-3-one). AMPO forming bacteria were enriched in the rhizosphere of benzoxazinoid-producing maize and could use MBOA as carbon source. We identified a 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 , did not form AMPO nor was 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 benzoxazinoid metabolisation gene whose carriers successfully colonize the maize rhizosphere and thereby shape the plant’s chemical environmental footprint. Maize root bacteria were investigated for how they cope with the antimicrobial root exudates of their host plant. A gene cluster was identified, allowing the bacteria to metabolise these compounds and to specialize on the exudates of their host.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 45/47 / 45/70 / 45/77 / 49/22 / 49/23 / 49/39 / 631/326/171/1818 / 631/326/2565/2134 / 631/326/325/1506 / 64 / 82/80 / Bacteria / Bacterial Proteins - genetics / Bacterial Proteins - metabolism / Benzoxazines - metabolism / Bioactive compounds / Carbon / Carbon sources / Corn / Deletion mutant / Ecological footprint / Exudates / Gene deletion / Host plants / Host specificity / Humanities and Social Sciences / Metabolites / Microbiomes / Microbiota - genetics / multidisciplinary / Multigene Family / Plant Roots - metabolism / Plant Roots - microbiology / Rhizosphere / Roots / Science / Science (multidisciplinary) / Soil ecology / Soil Microbiology / Sphingomonadaceae - enzymology / Sphingomonadaceae - genetics / Sphingomonadaceae - metabolism / Zea mays - microbiology