Journal Article

Photosynthetic activity in winter needles of the evergreen tree <i>Taxus cuspidata</i> at low temperatures

Ayumi Tanaka

in Tree Physiology

Volume 27, issue 5, pages 641-648
Published in print May 2007 | ISSN: 0829-318X
Published online May 2007 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/27.5.641
Photosynthetic activity in winter needles of the evergreen tree Taxus cuspidata at low temperatures

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Photosystems harvest light energy, yet this energy cannot be efficiently employed for CO2 assimilation at the below-freezing temperatures to which plants are typically exposed during winter in the temperate and boreal zones. To elucidate the mechanisms whereby this energy is dissipated, I evaluated performance of photosystems in winter needles of the evergreen tree Taxus cuspidata Sieb. et Zucc. Chloroplasts were localized adjacent to plasma membranes in needle cells in summer, whereas they congregated together in the centers of the cells during winter. When winter needles were acclimated to a temperature of 20 °C, their chloroplasts gradually dispersed to the edges of the cells, as in the summer. Acclimation-dependant relocalization coincided with changes in CO2 uptake. Examination of photosystem II fluorescence kinetics in winter needles indicated that the quinone electron acceptor (QA) reduction rate exceeded the QA oxidation rate at low temperatures. The majority of QA remained reduced even when winter needles were subjected to a temperature of –5 °C at low irradiance.

Keywords: electron transport; fluorescence; frost; gas exchange; photosynthesis

Journal Article.  0 words. 

Subjects: Plant Sciences and Forestry

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