The sugar porter gene family of Laccaria bicolor: function in ectomycorrhizal symbiosis and soil‐growing hyphae

Abstract

Summary Formation of ectomycorrhizas, a symbiosis with fine roots of woody plants, is one way for soil fungi to overcome carbohydrate limitation in forest ecosystems. Fifteen potential hexose transporter proteins, of which 10 group within three clusters, are encoded in the genome of the ectomycorrhizal model fungus Laccaria bicolor. For 14 of them, transcripts were detectable. When grown in liquid culture, carbon starvation resulted in at least twofold higher transcript abundances for seven genes. Temporarily elevated transcript abundance after sugar addition was observed for three genes. Compared with the extraradical mycelium, ectomycorrhiza formation resulted in a strongly enhanced expression of six genes, of which four revealed their highest observed transcript abundances in symbiosis. A function as hexose importer was proven for three of them. Only three genes, of which just one was expressed at a considerable level, revealed a reduced transcript content in mycorrhizas. From gene expression patterns and import kinetics, the L. bicolor hexose transporters could be divided into two groups: those responsible for uptake of carbohydrates by soil‐growing hyphae, for improved carbon nutrition, and to reduce nutrient uptake competition by other soil microorganisms; and those responsible for efficient hexose uptake at the plant–fungus interface.

Generating Phenotypic Diversity in a Fungal Biocatalyst to Investigate Alcohol Stress Tolerance Encountered during Microbial Cellulosic Biofuel Production

“…Filamentous fungal transporters appear to hold diverse functional roles notably in plant-fungi symbiosis [55-57] pathogenicity [58,59], and ethanol production and tolerance [48,50,60-62]. In regards to tolerance, transcriptional studies have identified alcohol responsive genes associated with sugar transport [50,63,64].…”

Arbuscular Mycorrhizal Fungi Regulate the Growth and Phyto-Active Compound of Salvia miltiorrhiza Seedlings

“…AMFs improve the host plants' absorption of water and nutrients from the soil; in return, 20% of the carbon that the plants fixed on their own is transferred to the fungi [12,13]. If carbon acquired from the plant is reduced, N may have a negative impact on arbuscular mycorrhizae (AM) abundance [14].…”

The role of mycorrhizal associations in plant potassium nutrition

“…Mycorrhizal fungi participate actively to plant development (Smith and Read, 2008) by improvement of access to nutrients, particularly when resources become scarce. In turn, vegetal partners provide up to 20–25% of photosynthetic carbohydrates to their symbionts (López et al, 2008). The improvement of plant nutrition through mycorrhizal symbioses and the molecular bases of nutrient transfer are currently well studied for phosphorus (Javot et al, 2007; Plassard and Dell, 2010) and nitrogen (Müller et al, 2007; Jin et al, 2012).…”