Hormones are small signaling molecules that travel between cells and deliver messages to switch on and off specific genes — affecting behavior, environmental responses and growth. Human hormones include testosterone, insulin and the aptly named growth hormone. Plant hormones are an entirely different set of chemical messengers, which modulate activities such as stem growth, leaf and flower production, root patterning and coping with environmental disruption.
These are just the sorts of tasks that plant biologists seek to understand with precision as the pressure increases to feed a growing population amid unchecked climate change. But hormones in plants affect such a wide variety of genes and plant activities that the fine details of hormone responses are — at best — murky.
Researchers at the University of Washington have developed a novel toolkit based on modified yeast cells to tease out how plant genes and proteins respond to auxin, the most ubiquitous plant hormone. Their system, described in a paper published Sept. 19 in the Proceedings of the National Academy of Sciences, allowed them to decode auxin’s basic effects on the diverse family of genes that plants utilize to detect and interpret auxin-driven messages.
“Auxin has different messages in different contexts,” said senior author and UW biology professor Jennifer Nemhauser. “One cell responds to auxin one way, while its neighbor does the exact opposite — two different responses from the same chemical. What inside these cells is happening to deliver opposite messages?”
This image shows two thale cress plants (Arabidopsis thaliana), common weeds that are distant cousins of mustard and other cruciferous vegetables. The one on the left is wild-type, capable of responding normally to signals provided by the hormone auxin. The plant on the right is a mutant, lacking a key gene that can respond to auxin messages, resulting in severely stunted growth.Public Library of Science
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