Moy Andy, Le Sherry, Verhoeven Amy
Department of Biology, University of St. Thomas, St. Paul, MN, 55105, USA.
Physiol Plant. 2015 Oct;155(2):205-216. doi: 10.1111/ppl.12331. Epub 2015 Feb 27.
During autumn senescence, plants must disassemble the photosynthetic apparatus as nutrients are remobilized from the leaves. The goal of this study was to examine changes in relative abundance of photosynthetic proteins and pigments throughout autumn senescence in order to understand the mechanisms of photoprotection used during this process. We sampled leaves from two deciduous tree species [sugar maple (Acer saccharum Marsh.) and swamp white oak (Quercus bicolor Willd.)] throughout autumn during 2010 and 2013. Chlorophyll fluorescence was measured, thylakoids were isolated for western blotting with antibodies to individual proteins and pigment content was assessed. Both species retained high photochemical efficiency until late autumn and showed earlier onset of degradation of photosystem I relative to photosystem II. The species differed in the timing and pattern of degradation of individual photosynthetic proteins and pigments. In maple, there were increases in anthocyanins, more rapid degradation of light-harvesting proteins and enrichment of xanthophyll cycle pigments in late autumn. In oak, light-harvesting proteins were retained in higher abundance throughout autumn, PsbS levels increased during early autumn and lutein was enriched in late autumn samples. The results suggest that the species differ in strategies for photoprotection during autumn senescence.
在秋季衰老过程中，随着养分从叶片中被重新调动，植物必须拆解光合机构。本研究的目的是研究整个秋季衰老过程中光合蛋白和色素相对丰度的变化，以便了解该过程中使用的光保护机制。我们在2010年和2013年的整个秋季，从两种落叶树种[糖枫（Acer saccharum Marsh.）和沼生白栎（Quercus bicolor Willd.）]采集叶片。测量叶绿素荧光，分离类囊体用于针对个别蛋白质的蛋白质免疫印迹分析，并评估色素含量。两种树种在深秋之前都保持较高的光化学效率，并且相对于光系统II，光系统I的降解开始得更早。两种树种在个别光合蛋白和色素的降解时间和模式上存在差异。在枫树中，花青素增加，捕光蛋白降解更快，并且在深秋叶黄素循环色素富集。在栎树中，捕光蛋白在整个秋季都保持较高丰度，PsbS水平在初秋增加，并且在深秋样品中叶黄素富集。结果表明，两种树种在秋季衰老期间的光保护策略不同。
