Summary: Photorespiration is frequently considered a wasteful and inefficient process. However, mutant analysis demonstrated that photorespiration is essential for recycling of 2‐phosphoglycolate in C₃ and C₄ land plants, in algae, and even in cyanobacteria operating carboxysome‐based carbon (C) concentrating mechanisms. Photorespiration links photosynthetic C assimilation with other metabolic processes, such as nitrogen and sulfur assimilation, as well as C₁ metabolism, and it may contribute to balancing the redox poise between chloroplasts, peroxisomes, mitochondria and cytoplasm. The high degree of metabolic interdependencies and the pleiotropic phenotypes of photorespiratory mutants impedes the distinction between core and accessory functions. Newly developed synthetic bypasses of photorespiration, beyond holding potential for significant yield increases in C₃ crops, will enable us to differentiate between essential and accessory functions of photorespiration.

Plants require sunlight, water, CO2, and essential nutrients to drive photosynthesis and fulfill their life cycle. The photosynthetic apparatus resides in chloroplasts and fundamentally relies on transition metals as catalysts and cofactors. Accordingly, chloroplasts are particularly rich in iron (Fe), manganese (Mn), and copper (Cu). Owing to their redox properties, those metals need to be carefully balanced within the cell. However, the regulation of transition metal homeostasis in chloroplasts is poorly understood. With the availability of the arabidopsis genome information and membrane protein databases, a wider catalogue for searching chloroplast metal transporters has considerably advanced the study of transition metal regulation. This review provides an updated overview of the chloroplast transition metal requirements and the transporters involved for efficient photosynthesis in higher plants.

Generation of carbon skeletons for amino acid synthesis in some C3 plants resembles fluxes needed for CAM-type photosynthesis.

Analysis of an Arabidopsis mutant with a defect in photosystem II reveals that the integral thylakoid membrane protein PAM71 is involved in manganese and calciu

Manipulating the levels of the vitamin B6 salvage enzyme PDX3 reveals that alterations in vitamin B6 homeostasis and nitrogen metabolism are linked.