COLUMBIA, 11/10/11 (Op-Ed) -- Plants don't have eyes, but everyone has seen them point toward sunlight. Called "phototropism," this unusual ability hasn't been well understood until a recent study from University of Missouri scientists, who report in the journal Plant Cell how a critical protein helps regulate phototropism.
Two light-sensing proteins, phototropin 1 and phototropin 2, initiate phototropism after a third protein called NPH3 tags phototropin 1 with a substance called "ubiquitin," the researchers discovered, likening the process to hand signals at a baseball game.
Phototropin is the pitcher and NPH3 the catcher who coordinates the pitch with ubiquitin, a biochemical version of a hand signal, explained Mizzou biology professor and Bond Life Sciences Center researcher Mannie Liscum. "Prior to this study, no one knew how NPH3 and the phototropins cooperated to facilitate the signal," he said.
The plant's sunlight response is also dose-dependent. "In low-light conditions, phototropin 1 is modified with single ubiquitin proteins," Liscum said. "In high-light conditions, phototropin 1 is modified with multiple ubiquitin proteins."
The research may have implications beyond crop science, he added. "Many human disease pathologies are associated with alterations in ubiquitin-tagging."