Zygote wall of Chlamydomonas reinhardtii

Multilayered zygote wall of Chlamydomonas reinhardtii. Note the undulated algaenan containing layer (3), outermost callose containing layer (6) and fibrous hydroxyproline-rich glycoprotein (HRGPs) containing layers (1, 2, 4, and 5).
Mature zygotic wall of Chlamydomonas reinhardtii is made of six distinct layers in varying thicknesses, allowing the cells to survive under nutrient-limited and hostile environmental conditions. These wall layers are found to contain polysaccharides and lipids such as algaenan in addition to hydroxyproline-rich glycoproteins (HRGPs), major components of the vegetative wall. The individual components show similarity to extensins and callose that are found in the extracellular matrix of land plants. As chlorphyte algae like Chlamydomonas and land plants share a common ancestor, analysis of the algal cell wall is expected to shed light on evolution and biology of the extracellular matrix of land plants.