Exploring Anastomosis of Hyphae and Mating-Type Compatibility of Pochonia chlamydosporia Isolates of the Meloidogyne, Heterodera and Globodera Biotypes

The endophytic and nematophagous fungus Pochonia chlamydosporia is an efficient biological control agent of plant-parasitic nematodes. Isolates of the fungus can be allocated to a biotype group according to the nematode host, but it is unknown if genetic interchange can occur between different biotypes, which may affect their parasitic performance. An anastomosis assay was conducted in vitro to assess hyphae vegetative compatibility/incompatibility followed by a PCR-based mating-type assay genotyping of five isolates of P. chlamydosporia var. chlamydoporia of the Meloidogyne sp. (Pc10, Pc190, Pc309), Globodera sp. (Pc280) and Heterodera avenae (Pc60) biotypes, including 16 pairwise isolates combinations in four replicates. Pairwise combinations were tested on glass slides and mycelia were stained to confirm nuclei migration between anastomosing hyphae using fluorescence microscopy. Anastomosis only occurred between mycelium hyphae of the same isolate and biotype. Mating-type PCR-based molecular assays showed that all isolates were heterothallic. The MAT1-1 genotype was found in isolates Pc10, Pc190, Pc280, Pc309, and the MAT1-2 genotype in Pc60. The results showed a vegetative incompatibility among isolates, suggesting the occurrence of such interactions for their respective biotypes. Anastomosis and PCR mating-type results suggest that different fungal biotypes can occur in the same niche but that genetic incompatibility mechanisms, such as mating-type, may limit or impede viable heterokaryosis.