In my previous post, I shared the first ever image of plant stomata cells “breathing” which is the basis of photosynthesis and almost all the oxygen we ourselves breathe. I’m not done with plants yet!

To recap, stomata are microscopic pores on the surface of leaves and stems that control gas exchange (specifically, carbon dioxide and oxygen). They are surrounded by so-called guard cells which in turn contain chloroplasts, the cells that give leaves their green color. Crucially, chloroplasts provide the energy needed to open and close stomatal pores.

Chloroplasts are not static. They move within guard cells, primarily to maximize photosynthesis under low light and to avoid damage under intense light. This movement – generally known as cytoplasmic motion – is driven by specific filaments referred to as cp-actin filaments, which are found at the leading edge of every chloroplast.

Actin filaments act as a pulling force, like the action of a boat paddle. Importantly, chloroplasts don’t just move for the sake of moving; they move in response to light intensity, allowing them to optimize photosynthesis in weak light and protect themselves from damage in strong light. How wonderful is that?

Video: Chloroplasts in Motion

Scientific Reference

Kosei Iwabuchi and Shingo Takagi, “Actin-based mechanisms for light-dependent intracellular positioning of nuclei and chloroplasts in Arabidopsis”, Plant Signaling and Behavior, 2010, Vol 5: 8, 2010.