Fig. 7

Proposed model to show the functional roles of NoZEPs in N. oceanica under NL and HL conditions. Both NoZEP1 and NoZEP2 are functional in N. oceanica and suppressing either one impairs the synthesis of violaxanthin (the major light-harvesting carotenoid), accompanied by the attenuated levels of chlorophyll a and chloroplast membrane lipids. Under NL conditions (below the saturation light intensity), the mutant harvests less light and thus has lower photosynthetic growth than WT. Under HL conditions (above the saturation light intensity), as containing less pigments, the mutant cells are exposed to more light per cell than WT cells and thus likely subjected to more severe light stress (photoinhibition), leading to lowered growth of the mutant