A matter of quantity: The effect of chloroplast stromal phosphate levels on photosynthetic efficiency

Abstract

Phosphorus (P) is an essential mineral nutrient for plants, playing central roles in development, growth, and environmental responses. In the soil, P is available in the form of inorganic phosphate (Pi), which, once incorporated by plants, can be converted into nucleic acids, membrane lipids, and sugars. Pi is also necessary for ATP synthesis during photosynthesis, and its concentration in the chloroplast is linked to photosynthetic regulation. Environmental fluctuations and metabolic changes can alter chloroplastic Pi homeostasis, triggering acclimation responses to maintain photosynthetic performance (Bouain et al. 2022). Stromal Pi levels need to be high enough to sustain photophosphorylation without inhibiting Calvin-Benson cycle reactions (Grotjohann and Gräber 2002; Marcus et al. 2005). Therefore, plants strictly regulate Pi levels to avoid inhibition of photosynthesis.