期刊
PLANT PHYSIOLOGY AND BIOCHEMISTRY
卷 81, 期 -, 页码 121-127出版社
ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER
DOI: 10.1016/j.plaphy.2014.01.014
关键词
Chlorophyll fluorescence; Cyanobacteria; beta-Carotene; 77 K fluorescence spectra; State transitions
beta-Carotene is the only carotenoid present in the core complexes of Photosystems I and II. Its proximity to chlorophyll a molecules enables intermolecular electronic interactions, including beta-carotene to chlorophyll a electronic excitation transfers. However, it has been well documented that, compared to chlorophylls and to phycobilins, the light harvesting efficiency of beta-carotenes for photosynthetic O-2 evolution is poor. This is more evident in cyanobacteria than in plants and algae because they lack accessory light harvesting pigments with absorptions that overlap the beta-carotene absorption. In the present work we investigated the light harvesting role of beta-carotenes in the cyanobacterium Synechococcus sp. PCC 7942 using selective beta-carotene excitation and selective Photosystem detection of photo-induced electron transport to and from the intersystem plastoquinones (the plastoquinone pool). We report that, although selectively excited beta-carotenes transfer electronic excitation to the chlorophyll a of both photosystems, they enable only the oxidation of the plastoquinone pool by Photosystem I but not its reduction by Photosystem II. This may suggest a light harvesting role for the beta-carotenes of the Photosystem I core complex but not for those of the Photosystem II core complex. According to the present investigation, performed with whole cyanobacterial cells, the lower photosynthesis yields measured with beta-Car-absorbed light can be attributed to the different excitation trapping efficiencies in the reaction centers of PSI and PSII. (C) 2014 Elsevier Masson SAS. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据