Mitochondrial AOX Supports Redox Balance of Photosynthetic Electron Transport, Primary Metabolite Balance, and Growth in under High Light.

When leaves receive excess light energy, excess reductants accumulate in chloroplasts. It is suggested that some of the reductants are oxidized by the mitochondrial respiratory chain. Alternative oxidase (AOX), a non-energy conserving terminal oxidase, was upregulated in the photosynthetic mutant of , , which accumulated reductants in chloroplast stroma.

Elevated CO2-induced changes in mesophyll conductance and anatomical traits in wild type and carbohydrate-metabolism mutants of Arabidopsis.

Decreases in photosynthetic rate, stomatal conductance (gs), and mesophyll conductance (gm) are often observed under elevated CO2 conditions. However, which anatomical and/or physiological factors contribute to the decrease in gm is not fully understood. Arabidopsis thaliana wild-type and carbon-metabolism mutants (gwd1, pgm1, and cfbp1) with different accumulation patterns of non-structural carbohydrates were grown at ambient (400 ppm) and elevated (800 ppm) CO2.

Sink-Source Balance and Down-Regulation of Photosynthesis in Raphanus sativus: Effects of Grafting, N and CO2.

To clarify whether excessive accumulation of total non-structural carbohydrate (TNC) causes down-regulation of photosynthesis in Raphanus sativus, we manipulated sink-source balance to alter TNC levels in source leaves and examined its effects on photosynthetic characteristics, whole-plant biomass allocation and anatomical characteristics of leaves and petioles. Comet and Leafy varieties with large and small hypocotyls were reciprocally grafted to change hypocotyl sink strength. They were grown at high or low nitrogen (N) availability and at elevated or ambient CO2.

Mitochondrial Alternative Pathway-Associated Photoprotection of Photosystem II is Related to the Photorespiratory Pathway.

Respiratory electron transport has two ubiquinol-oxidizing pathways, the cytochrome pathway (CP) and the alternative pathway (AP). The AP, which is catalyzed by the alternative oxidase (AOX), is energetically wasteful but may alleviate PSII photoinhibition under light conditions excessive for photosynthesis. However, its mechanism remains unknown.