Plant & zo
The science of plants and more
Light lets plants breathe
Researchers from Singapore discovered how light lets plants breathe. Plants breathe using stomata, these are special cells located on the underside of the leaf. In contrast to normal plant cells, these cells are not connected to each other with a cell wall. This is creating a pore through which air can enter the airspace of the leaf.
With air, CO2 for photosynthesis is entering. And with the air that leaves the leaf, water exits as well. By warm weather the plant tries to prevent too much water leaving by closing the stomata. But with lots of light, the plant sets them wide open, so that as much as possible CO2 is available for photosynthesis. It is therefore important to have a balance between environment, the amount of stomata, and their opening.
Not surprising, the plant is regulating this tightly. Part of this is regulating the number of stomata on the leaf. The gene SPEECHLESS is regulating this. Is this gene on then the cell develops into stomata. The protein YODA is making sure that normally SPEECHLESS is off, to prevent all cells turning into stomata.
Singaporean researches now have discovered that light can turn off YODA. Light has a messenger HY5. If there is light, then the protein HY5 is stable, but how darker it is how more likely it is that HY5 breaks down. Therefore, the amount of HY5 is a direct measurement of the amount of light. Part of HY5 job is to turn on the production of STOMAGEN, which in turn turns off YODA, turning SPEECHLESS on and allowing stomata to form.
The amount of light is reflected in the amount of HY5, and so in the amount of SPEECHLESS turned on. This explains how plants in brighter lights have more stomata that their counter parts in the shadow, and how they can breathe a little deeper.
Shenqi Wang, Zimin Zhou, Rini Rahiman, Grace Sheen Yee Lee, Yuan Kai Yeo, Xin Yang and On Sun Lau. (2021) Light regulates stomatal development by modulating paracrine signaling from inner tissues. Nature Communications 12, 3403.