Lumen alkalization under elevated bicarbonate concentration outside isolated thylakoids of higher plants.

Elevated bicarbonate concentration increases thylakoid lumen pH and stimulates electron transport in isolated pea chloroplasts, highlighting bicarbonate as a potential regulator.

• Why it matters: Understanding how stromal bicarbonate influences lumen pH is crucial because pH regulation affects photosynthetic efficiency and energy conversion processes in plants.
• What they did: Researchers increased bicarbonate levels in isolated pea thylakoids and measured effects on lumen pH and electron transport, focusing on photosystem I and II activities.
• The result: Bicarbonate raised lumen pH and enhanced electron flow via photosystem I, suggesting mechanisms involving proton efflux and bicarbonate transport, thus revealing a new regulatory role in photosynthesis.