Regulation of mating genes during arbuscular mycorrhizal isolate co-existence-where is the evidence?

A recent study published by Mateus et al. [1] claimed that 18 mating-related genes are differentially expressed in the model arbuscular mycorrhizal fungus (AMF) Rhizophagus irregularis when genetically distinct fungal strains co-colonize a host plant. To clarify the level of evidence for this interesting conclusion, we first aimed to validate the functional annotation of these 18 R. irregularis genes using orthology predictions. These analyses revealed that, although sequence relationship exists, only 2 of the claimed 18 R. irregularis mating genes are potential orthologues to validated fungal mating genes. We also investigated the RNA-seq data from Mateus et al. [1] using classical RNA-seq methods and statistics. This analysis found that the over-expression during strain co-existence was not significant at the typical cut-off of the R. irregularis strains DAOM197198 and B1 in plants. Overall, we do not find convincing evidence that the genes involved have functions in mating, or that they are reproducibly up or down regulated during co-existence in plants.

Automated summary

A recent study claimed differential expression of 18 mating-related genes in Rhizophagus irregularis when genetically distinct fungal strains co-colonize a host plant, but further investigation revealed only 2 potential orthologues to validated fungal mating genes. RNA-seq data analysis also found the over-expression during strain co-existence in plants was not significant.