When flu season arrives, you might start eyeing citrus fruit closely or washing your hands with extra diligence. You鈥檙e not alone. One species of plant, Arabidopsis thaliana, also anticipates an impending infection and guards itself against it.
The secret to its success is an immune system that is partially regulated by light, allowing it to fight off a pathogen that attacks at dawn.
of Duke University in Durham, North Carolina, and colleagues studied how a small flowering plant, Arabidopsis thaliana, defends itself against a fungus-like pathogen, Hyaloperonospora arabidopsidis, which covers the plant鈥檚 leaves in a white downy mildew.
Advertisement
The team found that plants engineered to lack 22 genes, all partly regulated by light-driven circadian rhythms, were unable to resist attack. Plants with the genes did not succumb to the pathogen.
Dawn attack
The pathogen attacks at dawn, so to fight it the plants should raise their defences overnight. Sure enough, the team found that the 22 defence genes are all expressed in the evening
鈥淲e discovered that these defence genes have a rhythm,鈥� Dong says. 鈥淲e never really thought about plants鈥� immune systems this way, but it actually makes a lot of sense.鈥�
, an expert on plant circadian rhythms at Dartmouth College in Hanover, New Hampshire, is excited by the study as it is the first to find a convincing mechanism for the relationship between the immune system and light.
鈥淭his is such a nice solid study that really makes it clear there is a link between timing and resistance to at least this one pathogen,鈥� McClung says. 鈥淚t is really exciting and gratifying.鈥�
Journal reference:
