Tree Biology

In a previous article, I described important new research by Mark Estelle and his colleagues showing how auxin works. Here is a useful diagram by Nicolle Rager Fuller, courtesy of the National Science Foundation, showing the new understanding of auxin's action.

Auxin works in a cell by binding specifically to a protein called TIR1. The combination of TIR1 and auxin, along with a couple of other proteins, destroys a repressor protein that stops growth genes from being expressed. Once these growth genes are activated, they are expressed and produce proteins that control plant growth. Growth genes could include those that promote cell elongation and division, or differentiation. This new understanding of how auxin works does not tell us everything about how auxin promotes root formation, branch suppression and all its other roles. It gives scientists new ways to do experiments to reveal these details.