A laser uncovers the logic of the stomata function

What you do is sometimes determined by what your neighbours do. Scientists believe that this extends to stomatal behaviour. Stomata are pores placed at the plant surface that allow gas exchange with the atmosphere. When entire plants are exposed to light, all their stomata open widely to maximize the uptake of CO2 for photosynthesis. In contrast, in the dark all the stomata remain closed to prevent an excessive water loss. In the inaugural issue of PLoS ONE, the teams of both Laura Serna and Jorge Casal have published the secret messages underlying stomatal behaviour by illuminating, for first time, individual stomata of the flowering plant Arabidopsis thaliana, whereas their neighbours were maintained in the dark. That stomata open independently of the behaviour of those around them is only a part of the secret they have uncovered.

They also found that the stomatal autonomous opening depends on the releasing of a light receptor, named PHOTOTROPIN1, from the cell membrane to the interior cell. These researches unravelled that, in addition to this process, stomatal opening requires changes directly induced by light in the interior cell. The nature of such as changes is unknown, and it brings an exciting challenge for the future.

But, why do stomata act with independence of the behaviour of their neighbours? The teams of Jorge Casal and Laura Serna measured the incident irradiance in a leaf partially shaded by another. They found that the incident irradiance is below the saturation value of phototropin action in the shade region and above saturation in the lighted area. Interestingly, such a change occurs in micrometric distance smaller than the cell distance between stomata neighbours. The stomata autonomy confers an advantage on the plant, which opens the lighted stoma, while maintains the shaded neighbour closed. This behaviour optimises the balance between water loss and CO2 acquisition.

The study performed by the teams of Laura Serna and Jorge Casal not only provides convincing evidence on the logic of the autonomous stomatal behaviour, and on the cellular mechanism underlying such as process. It also provides the background to inspire readers outside their own immediate field to consider the cellular autonomy and cell signalling of many other light-induced processes.

Citation: Cañamero RC, Boccalandro H, Casal J, Serna L (2006) Use of Confocal Laser as Light Source Reveals Stomata-Autonomous Function. PLoS ONE 1(1): e36. doi:10.1371/journal.pone.0000036