Journal Article

Effects of photooxidation on membrane integrity in <i>Salix nigra</i> seeds

Gonzalo Roqueiro, Graciela B. Facorro, Mónica G. Huarte, Emilio Rubín de Celis, Fernando García, Sara Maldonado and Horacio Maroder

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 105, issue 6, pages 1027-1034
Published in print June 2010 | ISSN: 0305-7364
Published online March 2010 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcq067
Effects of photooxidation on membrane integrity in Salix nigra seeds

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  • Ecology and Conservation
  • Evolutionary Biology
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Background and Aims

Salix nigra seeds are desiccation-tolerant, as are orthodox seeds, although in contrast to other orthodox seeds they lose viability in a few weeks at room temperature. They also differ in that the chloroplasts of the embryo tissues conserve their chlorophyll and endomembranes. The aim of this paper was to investigate the role of chlorophyll in seed deterioration.

Methods

Seeds were aged at different light intensities and atmospheric conditions. Mean germination time and normal and total germination were evaluated. The formation of free radicals was assessed using electronic spin resonance spectroscopy, and changes in the fatty acid composition from phospholipids, galactolipids and triglycerides using gas–liquid chromatography. Membrane integrity was studied with electronic spin resonance spin probe techniques, electrolyte leakage and transmission electron microscopy.

Key Results

Light and oxygen played an important role in free-radical generation, causing a decrease in normal germination and an increase in mean germination time. Both indices were associated with a decrease in polyunsaturated fatty acids derived from membrane lipids as phospholipids and galactolipids. The detection of damage in thylakoid membranes and an increase in plasmalemma permeability were consistent with the decrease in both types of lipids. Triglycerides remained unchanged. Light-induced damage began in outermost tissues and spread inwards, decreasing normal germination.

Conclusions

Salix nigra seeds were very susceptible to photooxidation. The thylakoid membranes appeared to be the first target of the photooxidative process since there were large decreases in galactolipids and both these lipids and the activated chlorophyll are contiguous in the structure of that membrane. Changes in normal germination and mean germination time could be explained by the deteriorative effects of oxidation.

Keywords: Embryo membrane integrity; free radicals; orthodox seed; photooxidation; Salicaceae seeds; Salix nigra; seed chlorophyll; seed lipid peroxidation; thylakoids; willow seeds

Journal Article.  5316 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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