Science Advances: Scientists discover the mechanism that plants use to control their mouths

Rising concentrations of carbon dioxide (CO2) in the atmosphere can lead to plant stomatal closure, which can seriously affect transpiration and water loss, photosynthesis, and plant growth
.
But until now, it remains unclear how plants sense changes in CO2 concentrations in the environment and signal
the opening and closing of stomata.
Recently, scientists in the United States, Estonia and Finland discovered a molecular pathway
that plants use to direct their own "breathing" of CO2.
The results were published in the journal Science Advances, "Stomatal CO2/bicarbonate sensor consists of two interacting protein kinases, Raf-like HT1 and non-kinase-activity activity requiring MPK12/MPK4
。

The researchers found that in a low-CO2 environment, a protein kinase called HT1 phosphorylates and activates the negative regulatory protein kinase CBC1 downstream, forcing guard cells on both sides of the stomata to swell and keep the stomata open for as long as possible to absorb carbon dioxide and meet the needs
of photosynthesis.
When plants sense an increase in CO2 levels, the second protein complex, MPK4/MPK12, inhibits the activity of HT1 and its downstream CBC1 kinase through direct interaction with HT1, resulting in stomatal closure
.
The results show that MPK4/12 and HT1 together constitute a long-sought stomatal CO2/bicarbonate sensor
upstream of plant CBC1 kinase.

This research not only provides new insights into the complex processes of plant respiration, but also opens up new possibilities
for breeding more robust crops in the future.