The Chlorophyll b Reductase NOL Participates in Regulating the Antenna Size of Photosystem II in Arabidopsis Thaliana

Chlorophyll exists as chlorophyll-protein complexes in thylakoid membranes. The light-harvesting complexes of photosystem II (LHCII) and CP43/CP47 are the peripheral and core antenna, respectively, of the photosystem. Chlorophyll b exists in LHCII but not in the core antenna complex, suggesting that the LHCII level is closely related to the amount of chlorophyll b. The first step of the degradation of chlorophyll b is catalysed by chlorophyll b reductase (NYC1 and NOL). In this report, study found that the chlorophyll content was significantly lower and that the chlorophyll a/b ratio was higher in NOL over-expressing Arabidopsis thaliana plants than in wild type plants. Low temperature fluorescence spectra of the leaves and western blotting analysis revealed that photosystem II had a small antenna size in the NOL over-expressing plants. These results suggest that NOL is involved in the regulation of the antenna size of photosystem II.