Leaf chlorosis in oilseed rape plants (Brassica napus) grown on cadmium-polluted soil: causes and consequences for photosynthesis and growth |
| |
Authors: | Aurore Baryla Patrick Carrier Fabrice Franck Claude Coulomb Claire Sahut Michel Havaux |
| |
Institution: | (1) CEA/Cadarache, DSV, DEVM, Laboratoire d'Ecophysiologie de la Photosynthèse, 13108 Saint-Paul-lez-Durance, France, FR;(2) CEA/Cadarache, DCC, Département d'Entreposage et de Stockage des Déchets, 13108 Saint-Paul-lez-Durance, France, FR;(3) Laboratoire de Photobiologie, Université de Liège, 4000 Liège, Belgium, BE;(4) Laboratoire de Cytologie et Pathologie Végétales, Université d'Avignon, 84000 Avignon, France, FR |
| |
Abstract: | Brassica napus L. (oilseed rape) was grown from seeds on a reconstituted soil contaminated with cadmium (100 mg Cd kg−1 dry soil), resulting in a marked chlorosis of the leaves which was investigated using a combination of biochemical, biophysical
and physiological methods. Spectroscopic and chromatographic analyses of the photosynthetic pigments indicated that chlorosis
was not due to a direct interaction of Cd with the chlorophyll biosynthesis pathway. In addition, mineral deficiency and oxidative
stress were apparently not involved in the pigment loss. Leaf chlorosis was attributable to a marked decrease in the chloroplast
density caused by a reduction in the number of chloroplasts per cell and a change in cell size, suggesting that Cd interfered
with chloroplast replication and cell division. Relatively little Cd was found in the chloroplasts and the properties of the
photosynthetic apparatus (electron transport, protein composition, chlorophyll antenna size, chloroplast ultrastructure) were
not affected appreciably in plants grown on Cd-polluted soil. Depth profiling of photosynthetic pigments by phase-resolved
photoacoustic spectroscopy revealed that the Cd-induced decrease in pigment content was very pronounced at the leaf surface
(stomatal guard cells) compared to the leaf interior (mesophyll). This observation was consistent with light transmission
and fluorescence microscopy analyses, which revealed that stomata density in the epidermis was noticeably reduced in Cd-exposed
leaves. Concomitantly, the stomatal conductance estimated from gas-exchange measurements was strongly reduced with Cd. When
plants were grown in a high-CO2 atmosphere (4,000 μl CO2 l−1), the inhibitory effect of Cd on growth was not cancelled, suggesting that the reduced availability of CO2 at the chloroplast level associated with the low stomatal conductance was not the main component of Cd toxicity in oilseed
rape.
Received: 14 July 2000 / Accepted: 27 August 2000 |
| |
Keywords: | :Brassica (Cd toxicity) Cadmium Chlorophyll Chloroplast Photosynthesis Stomata |
本文献已被 PubMed SpringerLink 等数据库收录! |
|