Cyclic electron transport pathways around photosystems I and II: Working together

Area of Science:

• Plant Physiology
• Photosynthesis Research
• Biochemistry

Background:

• Cyclic electron transport (CET) around photosystems I and II (PSI and PSII) is crucial for photosynthesis but often studied separately.
• Anoxygenic photosynthesis, encompassing CET, differs from oxygenic photosynthesis in O2 evolution and CO2 assimilation.
• Previous research on CET-PSI has yielded conflicting results, particularly regarding its role in non-stressed C3-plants.

Purpose of the Study:

• To re-evaluate the contribution of CET-PSI and CET-PSII to plant photosynthesis.
• To highlight the interconnectedness of CET-PSI and CET-PSII studies.
• To explore the potential of photoacoustic techniques for quantifying anoxygenic photosynthesis.

Main Methods:

• Analysis of existing data on CET-PSI and CET-PSII quantification.
• Critique of Antimycin A's role as a CET-PSI inhibitor, considering its primary effect on CET-PSII.
• Exploration of photoacoustic techniques for measuring anoxygenic photosynthesis.

Main Results:

• The contribution of CET-PSI in non-stressed C3-plants may be overestimated.
• CET-PSII and overall anoxygenic photosynthesis might be underestimated.
• Antimycin A's inhibitory effects are more pronounced on CET-PSII than CET-PSI.
• CET-PSI and CET-PSII cannot be effectively studied in isolation.

Conclusions:

• Overestimation of CET-PSI and underestimation of CET-PSII in plants are likely.
• Anoxygenic photosynthesis may play a more significant role than previously thought.
• Photoacoustic methods offer a promising avenue for accurate quantification of anoxygenic photosynthesis, including CET-PSII.