Abstract
• Ectomycorrhizal fungi play a key role in forests by establishing mutualistic symbioses with woody plants. Genome analyses have identified conserved symbiosis-related traits among ectomycorrhizal fungal species, but the molecular mechanisms underlying host-specificity remain poorly known.
• We sequenced and compared the genomes of seven species of milk-cap fungi (Lactarius, Russulales) with contrasted host-specificity. We also compared these genomes with those of symbiotic and saprotrophic Russulales species aiming to identify genes involved in their ecology and host-specificity.
• The size of Lactarius genomes is significantly larger than other Russulales species, owing to a massive accumulation of transposable elements and duplication of dispensable genes. As expected, their repertoire of genes coding for plant cell wall degrading enzymes is restricted, but they retained a substantial set of genes involved in microbial cell wall degradation. Notably, Lactarius species showed a striking expansion of genes encoding proteases, such as secreted ectomycorrhiza-induced sedolisins. A high copy number of genes coding for small secreted LysM proteins and Lactarius-specific lectins were detected, which may be linked to host-specificity.
• This study revealed a large diversity in the genome landscapes and gene repertoires within Russulaceae. The known host-specificity of Lactarius symbionts may be related to mycorrhiza-induced species-specific genes, including secreted sedolisins.
• We sequenced and compared the genomes of seven species of milk-cap fungi (Lactarius, Russulales) with contrasted host-specificity. We also compared these genomes with those of symbiotic and saprotrophic Russulales species aiming to identify genes involved in their ecology and host-specificity.
• The size of Lactarius genomes is significantly larger than other Russulales species, owing to a massive accumulation of transposable elements and duplication of dispensable genes. As expected, their repertoire of genes coding for plant cell wall degrading enzymes is restricted, but they retained a substantial set of genes involved in microbial cell wall degradation. Notably, Lactarius species showed a striking expansion of genes encoding proteases, such as secreted ectomycorrhiza-induced sedolisins. A high copy number of genes coding for small secreted LysM proteins and Lactarius-specific lectins were detected, which may be linked to host-specificity.
• This study revealed a large diversity in the genome landscapes and gene repertoires within Russulaceae. The known host-specificity of Lactarius symbionts may be related to mycorrhiza-induced species-specific genes, including secreted sedolisins.
| Original language | English |
|---|---|
| Journal | New Phytologist |
| Volume | 235 |
| Issue number | 1 |
| Pages (from-to) | 306-319 |
| ISSN | 0028-646X |
| DOIs | |
| Publication status | Published - 2022 |
Keywords
- Comparative genomics
- Ectomycorrhizal fungi
- Proteases
- Russulales
- Trait evolution