Guard cells in fern stomata are connected by plasmodesmata, but control cytosolic Ca2+ levels autonomously

What is it about?

Stomata are tiny pores in the leaf surface, which enable the uptake of CO2 for photosynthesis. Opening of stomata in seed plants is forced by uptake of potassium ions into two guard cells, whereas calcium signals play an important role in stomatal closure. We compared guard cells of ferns with those of seed plants and found that potassium channels and calcium signals are very similar. However, in fern stomata fluorescent dyes could move from one guard cell to its neighbor, whereas such connections are normally not found in seed plants. We propose that the interconnection of guard cells has been modified during evolution, which could be related to differences in the way that stomata open and close, in ferns and seed plants.

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