MYCOLab Ai Logo - gold and army green

Stochastic Nuclear Organization and Host-Dependent Allele Contribution in Rhizophagus irregularis

Summary

This research investigates how a beneficial soil fungus that forms partnerships with plants maintains genetic diversity within individual fungi. The study reveals that these fungi have a complex and dynamic genetic organization that can change depending on which plant they interact with. This has important implications for agriculture and ecosystem health. Impacts on everyday life: – Better understanding of how beneficial fungi help plants grow could lead to improved crop yields – Insights into plant-fungal partnerships could help develop more sustainable farming practices – Knowledge of fungal genetics could help select better fungal strains for specific crops – Understanding these relationships helps explain how plants and fungi have co-evolved successfully for millions of years – Could lead to reduced need for chemical fertilizers in agriculture

Background

Arbuscular mycorrhizal (AM) fungi are crucial plant symbionts that provide various benefits to their hosts. However, these benefits vary among fungal individuals, with genetic variation between symbionts significantly impacting plant performance. Within individual fungi, which contain millions of haploid nuclei sharing cytoplasm, genetic variation has been observed. In the model AM fungus Rhizophagus irregularis, several isolates are dikaryotes containing two genetically distinct nuclear types identified by mating-type locus identity. Their extremely coenocytic nature and lack of a known single nucleus stage raises questions about the origin, distribution and dynamics of this genetic variation.

Objective

To gain insight into the dynamic genetic makeup of the dikaryote-like R. irregularis C3 isolate and understand how different host plants affect its genetic variation through DNA and RNA sequencing at the mycelial individual, single spore and single nucleus levels.

Results

The analyses revealed that parallel spore and root culture batches can have widely variable ratios of two main genotypes in C3. Numerous polymorphisms were found with frequencies deviating significantly from the general genotype ratio, indicating diverse nucleotype populations. Host plant changes did not show consistent effects on nucleotype ratios after multiple rounds of subculturing. However, host plant identity had a major effect on allele-specific expression in C3.

Conclusion

The analyses indicate a highly dynamic and variable genetic organization in R. irregularis isolates. Random fluctuations in nucleotype ratios during spore formation, recombination events, high variability of non-tandemly repeated rDNA sequences, and host-dependent allele expression all contribute levels of variation that may explain the evolutionary success of these widespread symbionts.
  • Published in:BMC Genomics,
  • Study Type:Genomic Analysis,
  • Source: 10.1186/s12864-023-09126-6
Scroll to Top