A single gene is not enough for a selfish gene to kill spores.

Some pieces of DNA cheat the usual rules of inheritance. In Neurospora fungi, a selfish genetic element called Sk-3 ensures its own survival by killing almost all offspring spores that do not inherit it. Earlier work found a mutation called rfk-2 UV that stops this killing, but researchers did not know its exact location. In this study, scientists tracked down the mutation and discovered the gene behind it, named rfk-2. The gene works in a surprising way: its message gets spliced and edited, turning a stop signal into an instruction for the amino acid tryptophan so it can build a 102 amino acid protein. The researchers found that rfk-2 is necessary to kill rival spores, but it cannot do the job alone. Sk-3 relies on multiple genes working together.

Why it matters

This matters because selfish genetic elements like Sk-3 cheat Mendelian inheritance, spreading even if harmful. Knowing that killing requires multiple genes, not just one, changes how we think about their evolution and potential control. It also shows that even simple-looking genetic conflicts can be more complex than expected.

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