Molecular characterisation of rfk-2 identifies the gene required for spore killing by Neurospora Sk-3

A preprint posted to bioRxiv reports the molecular characterisation of rfk-2, a gene on Chromosome III of Neurospora crassa required for spore killing by the Sk-3 selfish genetic element.

Spore killing is a form of meiotic drive — a phenomenon in which a selfish genetic element biases its own inheritance by destroying competing gametes that do not carry it. In crosses between Sk-3 strains and spore-killing-sensitive (Sk-S) strains of Neurospora, nearly all offspring that fail to inherit Sk-3 are killed. An earlier study had isolated a mutation called rfk-2UV that disrupts this killing activity, but its precise location within the Sk-3 element was not known.

The authors now demonstrate that rfk-2UV is a T>G transversion within the protein-coding sequence of rfk-2, and that the rfk-2 gene is located on Chromosome III within the Sk-3 element itself. The molecular identification of this component advances the mechanistic understanding of how Sk-3 executes spore killing and how loss-of-function mutations can suppress it.

The study is relevant to the broader field of selfish genetic element biology, meiotic drive, and the evolutionary dynamics of genetic conflict. Neurospora remains a key model organism for fungal genetics. This work is a preprint and has not undergone peer review.