Early land plants evolved a simple but effective mechanism to place stomata away from each other
by Merced A. (2016)
In Atlas of Science Nov. 20,2016 –
Stomata are one of the key evolutionary features responsible for the successful colonization of land by plants.
A stoma is a pore surrounded by a pair of guard cells, when these cells are turgid and inflated the pore opens and when cells deflate the pore is closed.
This simple mechanism allows plants to optimize the amount of CO2 acquired for photosynthesis while reducing water loss due to transpiration.
Spacing of stomata in the epidermis, the external protective tissue of the plant, is important to ensure proper function and carbon fixation efficiency.
Mosses are of one of the firsts groups of plants to evolve stomata. Different from most plants, stomata of mosses and other early land plants are not located in leaves but on the spore producing capsule.
Our study investigated if the patterning and distribution of stomata in capsules of the moss Funaria follows a similar mechanism to that of flowering plants.
In flowering plants, namely the model organism Arabidopsis, stomata are place away from each other by a series of cell divisions of meristemoids, cells that actively divide to produce more meristemoids, epidermal cells or guard cells. This developmental process is regulated by genes and influence by the environment.
This study shows that stomata in mosses do not require meristemoids, instead stomata differentiate before the capsule begins to expand. Cells that will become stomata are align in files and separated by at least one cell. After the fate of the future stomata is decided, the surrounding cells divide perpendicular to it and differentiate into epidermal cells. Having stomata differentiate first, ensures that around 96-99% of stomata do not touch each other.