The Sugar Transporter MST1 Is Involved in Colonization of Rhizosphere and Rhizoplane by Metarhizium robertsii

• Published in: mSystems Vol. 6; no. 6; p. e0127721
• Main Authors: Dai, Jin, Mi, Wubin, Wu, Congcong, Song, Hui, Bao, Yuting, Zhang, Mingxiang, Zhang, Sufen, Fang, Weiguo
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 21.12.2021
• Subjects: Amino acids; Carbon; Carbon sources; Colonization; Fatty acids; Flowers & plants; Fructose; Fungi; Gene deletion; Genomes; Germination; Glucose; Host plants; Hydrogen; Mannose; Metarhizium; Metarhizium robertsii; Molecular modelling; Monosaccharides; Mycelia; Mycology; Oligosaccharides; Pathogens; Photosynthates; plant-symbiotic fungi; Plants; Raffinose; Research Article; Rhamnose; Rhizoplane; rhizoplane colonization; Rhizosphere; rhizosphere colonization; rhizosphere fungi; Sorbose; sugar transporter; Symbionts; Symbiosis; Terrestrial ecosystems; Variance analysis; Yeast; Metarhizium; rhizoplane colonization; plant-symbiotic fungi; rhizosphere colonization; rhizosphere fungi; sugar transporter
• ISSN: 2379-5077; 2379-5077
• DOI: 10.1128/mSystems.01277-21

It is widely recognized that plant-symbiotic fungi are supported by photosynthates; however, little is known about the molecular mechanisms underlying the utilization of plant-derived sugars by rhizospheric fungi. In the insect-pathogenic and plant-symbiotic fungus Metarhizium robertsii, we previously showed that the utilization of oligosaccharides by the transporter MRT ( raffinose transporter) is important for rhizosphere competency. In this study, we identified a novel monosaccharide transporter (MST1) that is involved in the colonization of the rhizoplane and acts additively with MRT to colonize the rhizosphere. MST1 is not involved in infection of insects by M. robertsii. MST1 is an H symporter and is able to transport a broad spectrum of monosaccharides, including glucose, sorbose, mannose, rhamnose, and fructose. Deletion of the gene impaired germination and mycelial growth in medium containing the sugars that it can transport. Homologs of MST1 were widely found in many fungi, including plant symbionts such as spp. and mycorrhizal fungi and plant pathogens such as Fusarium spp. This work significantly advances insights into the development of symbiotic relationships between plants and fungi. Over 90% of all vascular plant species develop an intimate symbiosis with fungi, which has an enormous impact on terrestrial ecosystems. It is widely recognized that plant-symbiotic fungi are supported by photosynthates, but little is known about the mechanisms for fungi to utilize plant-derived carbon sources. In the fungus Metarhizium robertsii, we identified a novel monosaccharide transporter (MST1) that is an H symporter and can transport a broad spectrum of monosaccharides, including glucose, sorbose, mannose, rhamnose, and fructose. MST1 is involved in the colonization of the rhizoplane and acts additively with the previously characterized oligosaccharide transporter MRT to colonize the rhizosphere. Homologs of MST1 were found in many fungi, including plant symbionts and plant pathogens, suggesting that the utilization of plant-derived sugars by MST1 homologs could also be important for other fungi to develop a symbiotic or parasitic relationship with their respective plant hosts.