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Genetic variation among progeny shapes symbiosis in a basidiomycete with poplar

Summary

This research examines how different genetic variations within a single fungal species affect its ability to form beneficial partnerships with poplar tree roots. Scientists studied 40 genetically distinct fungal strains derived from the same parent and found that they varied greatly in their success at colonizing tree roots, ranging from complete failure to excellent colonization. By analyzing the genes and gene expression of these strains, the team identified specific genetic regions that influence symbiosis formation and discovered that genetic diversity within this fungal species plays an important role in how effectively forest ecosystems function.

Background

Ectomycorrhizal (ECM) fungi form mutualistic symbioses with forest trees, facilitating nutrient and water acquisition. However, the molecular mechanisms governing ECM trait formation and the role of intraspecific fungal genetic variation remain inadequately understood. This study examines genetic and transcriptomic mechanisms underlying ECM symbioses using Pisolithus microcarpus, an ECM basidiomycete capable of colonizing poplar roots.

Objective

This study aims to investigate the genetic basis of ECM traits by analyzing phenotypic variation, genotypic variation, and transcriptomic profiles of 40 sibling monokaryons and their parental dikaryon of P. microcarpus in interaction with poplar. The research seeks to identify genomic regions and genes involved in ECM formation and to understand how intraspecific fungal diversity influences symbiotic interactions.

Results

A pronounced phenotypic continuum in ECM trait formation was observed among sibling monokaryons, ranging from incompatible to fully compatible strains. Extensive genetic recombination among monokaryons was detected through 13,140 genome-wide SNPs. QTL mapping identified four main genomic regions associated with three ECM traits, and 114 significant associations between copy number variations and ECM traits. Transcriptomic analysis revealed greater differentiation between fungal strains than between tissues, with distinct tissue-specific functional responses in ECM and free-living mycelia.

Conclusion

Intraspecific fungal genetic variation significantly shapes ECM symbiosis formation, with both parents and offspring exhibiting phenotypic variation in their ability to colonize poplar roots. The study demonstrates that ECM trait formation is a quantitative trait involving multiple genetic networks and reveals the complexity of host-fungal interactions at the molecular level. These findings highlight the crucial role of fungal genetic diversity in forest ecosystem functioning and symbiotic relationships.
  • Published in:New Phytologist,
  • Study Type:Experimental Study,
  • Source: PMID: 40772389, DOI: 10.1111/nph.70395
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