Research Selective autophagy fine-tunes plant immunity to promote cell survival during viral infection

When viruses infect plant cells, survival depends not only on activating immune defences, but also on preventing those defences from becoming destructive. A new study published in Science, led by Marion Clavel and Yasin Dagdas, shows that selective autophagy acts as a cellular balancing mechanism during viral infection. Rather than simply eliminating viral particles, autophagy helps plant cells respond to the internal damage caused by viruses, including stress to organelles such as mitochondria, chloroplasts and the endoplasmic reticulum.

The researchers found that, during infection by positive-sense RNA viruses, two metabolic enzymes, NIT1 and IMPDH, acquire an unexpected role in selective autophagy. When virus-induced organelle damage releases cellular contents into the cytosol, these enzymes change their physical state and help target immune regulators that promote cell death for degradation. In this way, autophagy functions as a molecular brake on excessive immunity: it prevents infected cells from dying too quickly, buys time for the plant to cope with infection, and improves the chances of survival. The work, carried out by researchers at the Gregor Mendel Institute of Molecular Plant Biology, Heidelberg University, the Max Planck Institute of Molecular Plant Physiology and international partners, reveals a new layer of immune regulation in plants.