Phosphate and sulfur limitation responses in the chloroplast of Chlamydomonas reinhardtii.

Phosphorus (P) and sulfur (S) are two macronutrients that photosynthetic organisms require in relatively large amounts despite their levels in the environment often being limited. Accordingly, to adapt to random changes in macronutrient concentrations, plants and algae must sense and respond in a coordinated fashion. The unicellular green alga Chlamydomonas reinhardti is a widely used model organism for the study of P and S stress responses. Herein, we review the current knowledge of P and S nutrient stress responses, highlighting the roles of P and S key global-regulator proteins in mediating signals that link P and S detection to different chloroplast nutrient stress responses.