Arbuscular mycorrhizal fungi heterokaryons have two nuclear populations with distinct roles in host-plant interactions.

Arbuscular mycorrhizal fungi (AMF) are prominent root symbionts that can carry thousands of nuclei deriving from two parental strains in a large syncytium. These co-existing genomes can also vary in abundance with changing environmental conditions. Here we assemble the nuclear genomes of all four publicly available AMF heterokaryons using PacBio high-fidelity and Hi-C sequencing.

A highly contiguous genome assembly reveals sources of genomic novelty in the symbiotic fungus Rhizophagus irregularis.

The root systems of most plant species are aided by the soil-foraging capacities of symbiotic arbuscular mycorrhizal (AM) fungi of the Glomeromycotina subphylum. Despite recent advances in our knowledge of the ecology and molecular biology of this mutualistic symbiosis, our understanding of the AM fungi genome biology is just emerging. Presented here is a close to T2T genome assembly of the model AM fungus Rhizophagus irregularis DAOM197198, achieved through Nanopore long-read DNA sequencing and Hi-C data.

Early branching arbuscular mycorrhizal fungus carries a small and repeat-poor genome compared to relatives in the Glomeromycotina.

The arbuscular mycorrhizal fungi (AMFs) are obligate root symbionts in the subphylum Glomeromycotina that can benefit land plants by increasing their soil nutrient uptake in exchange for photosynthetically fixed carbon sources. To date, annotated genome data from representatives of the AMF orders Glomerales, Diversisporales and Archaeosporales have shown that these organisms have large and highly repeated genomes, and no genes to produce sugars and fatty acids. This led to the hypothesis that the most recent common ancestor (MRCA) of Glomeromycotina was fully dependent on plants for nutrition.

Long reads and Hi-C sequencing illuminate the two-compartment genome of the model arbuscular mycorrhizal symbiont Rhizophagus irregularis.

Chromosome folding links genome structure with gene function by generating distinct nuclear compartments and topologically associating domains. In mammals, these undergo preferential interactions and regulate gene expression. However, their role in fungal genome biology is unclear.

Host identity influences nuclear dynamics in arbuscular mycorrhizal fungi.

The arbuscular mycorrhizal fungi (AMF) are involved in one of the most ecologically important symbioses on the planet, occurring within the roots of most land plants. Knowledge of even basic elements of AM fungal biology is still poor, with the discovery that AMF may in fact have a sexual life cycle being only very recently reported. AMF produce asexual spores that contain up to several thousand individual haploid nuclei of either largely uniform genotypes (AMF homokaryons) or nuclei originating from two parental genotypes (AMF dikaryons or heterokaryons).

Parasexual and Sexual Reproduction in Arbuscular Mycorrhizal Fungi: Room for Both.

Arbuscular mycorrhizal fungi (AMF) harbor thousands of nuclei in a large syncytium at all times. Although mating processes have not been observed in AMF, their cells and genomes show many signatures of sexual reproduction. Here, we describe how some of these signatures could also arise from parasexual processes in these widespread plant symbionts.

High intraspecific genome diversity in the model arbuscular mycorrhizal symbiont Rhizophagus irregularis.

Arbuscular mycorrhizal fungi (AMF) are known to improve plant fitness through the establishment of mycorrhizal symbioses. Genetic and phenotypic variations among closely related AMF isolates can significantly affect plant growth, but the genomic changes underlying this variability are unclear. To address this issue, we improved the genome assembly and gene annotation of the model strain Rhizophagus irregularis DAOM197198, and compared its gene content with five isolates of R.