More than 70 years after biologists identified the powerful plant hormone auxin, they have finally found how plant cells detect it.
Auxin plays a role in just about every aspect of plant growth, from roots to shoots. Gardeners use auxin-containing products to coax cuttings to take root and overdoses of auxin to kill weeds.
In the long search to understand how auxin works, biologists have had trouble figuring out step one: how a cell detects the hormone in the first place. In the May 26 Nature, two research groups independently report finding an auxin receptor in plant cells. It turns out to be a previously recognized molecule called transport inhibitor response 1 protein (TIR1).