Fungal Effectors That Help a Plant Disease Move Between Hosts

A common fungus called Sclerotinia sclerotiorum can act two ways. It sometimes causes serious disease in crops like rapeseed. But it can also live quietly inside wheat without causing harm. Scientists wanted to know how the fungus switches between these two lifestyles.

They looked at seven genes that make LysM proteins. These proteins help fungi stick to plant cells. Two of them, named SsLysM6 and SsLysM7, became more active in both situations. That means they matter whether the fungus is attacking or just living inside.

When researchers removed these two genes, the fungus struggled. It could not infect rapeseed well. It also could not colonize wheat properly. This showed that both genes help the fungus survive in very different plants.

The team tested the proteins directly. They found that SsLysM6 and SsLysM7 can grab onto chitin. Chitin is a tough material found in plant cell walls. By binding to it, the proteins may hide the fungus from the plant's immune system.

In lab tests, both proteins blocked immune responses. They stopped plants from making reactive oxygen species. They also stopped key defense signals from turning on. This helps explain how the fungus avoids being detected.

These results show that a few effector proteins can control how a fungus behaves. The same tools help it cause disease and live peacefully. This gives clues about how fungi evolve to adapt to many hosts.