Chlorophyll–carotenoid excitation energy transfer and charge transfer in <i>Nannochloropsis oceanica</i> for the regulation of photosynthesis

Abstract

Significance Manipulating the nonphotochemical quenching (NPQ) capabilities of photosynthetic organisms is known to result in increased crop productivity. However, optimization of yields also requires a detailed molecular understanding of the mechanism of NPQ in vivo with specific attention to the roles of the carotenoid zeaxanthin and various ∆pH-sensing proteins, such as photosystem II subunit S and stress-related antenna proteins (e.g., LHCX). Here, to investigate such in vivo NPQ mechanisms, we report transient absorption spectroscopy measurements on live cells of Nannochloropsis oceanica . We show that two fundamental processes proposed as NPQ mechanisms are active in N. oceanica and specifically require violaxanthin de-epoxidase as well as the LHCX1 protein. These findings have implications for optimizing the yields of algal biofuels.