"There are circumstances where you might want to disconnect the signals plants receive from the environment so they can survive," Bergmann said.
The protein, which the researchers dubbed SPEECHLESS, initiates the first of a three-step cell division process that leads to the formation of stomata in plants. Though structurally similar to SPEECHLESS, two other proteins involved in subsequent steps do not contain the same control region that is regulated by the signaling pathway. This provides a unique mechanism for the signaling pathway to control SPEECHLESS activity in a set of stem-cell-like cells and hence the ultimate development of stomata.
"If I were designing the leaf, that would be the part I would put under really tight control," Bergmann said. "It seems as if that's what plants have done."
Certain trade-offs exist for plants having too many or too few stomata. To help determine the number of stomata a newly sprouting leaf should form, the plant takes key factors about its surrounding climate-carbon dioxide levels, temperature and humidity-into account.
To perceive these factors, the plant uses the same signaling pathway used to control SPEECHLESS activity. The study identifies a critical junction that connects how a plant can sense environmental conditions with how this information is relayed to stomatal-development pathways. Thus, development of stomata can be altered "on the fly" to better enable the plant to cope with environmental conditions.
For example, a leaf contains fewer pores when carbon dioxide in the atmosphere is in abundance and more when it is limited. If conditions change, this multi-faceted signaling system can enable fine-tuning of stomatal development.
|Contact: Louis Bergeron|