Structural changes induced by NaCl in companion and transfer cells of Medicago sativa blades

Autor: F. Piton, M.-C. Verdus, Néziha Boughanmi, E. Ferjani, Pierrette Fleurat-Lessard, E. Bizid, Philippe Michonneau
Přispěvatelé: Laboratoire de Biologie et Physiologie Cellulaires, Faculté des Sciences de Bizerte [Université de Carthage], Université de Carthage - University of Carthage-Université de Carthage - University of Carthage, Transport des assimilats (TA), Université de Poitiers-Centre National de la Recherche Scientifique (CNRS), Glycobiologie et transports chez les végétaux (GTCV), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Membranes Biologiques, Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire de Biologie et Physiologie Végétales, Faculté des Sciences Mathématiques, Physiques et Naturelles de Tunis (FST), Université de Tunis El Manar (UTM)-Université de Tunis El Manar (UTM), Centre National de la Recherche Scientifique (CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)
Rok vydání: 2003
Předmět:
Zdroj: Protoplasma
Protoplasma, 2003, 220, pp.179-187. ⟨10.1007/s00709-002-0043-6⟩
Protoplasma, Springer Verlag, 2003, 220, pp.179-187. ⟨10.1007/s00709-002-0043-6⟩
ISSN: 1615-6102
0033-183X
Popis: Medicago sativa var. Gabes is a perennial glycophyte that develops new shoots even in high salinity (150 mM NaCl). In the upper exporting leaves, K(+) is high and Na(+) is low by comparison with the lower leaves, where Na(+) accumulation induces chlorosis after 4 weeks of NaCl treatment. By secondary ion mass spectroscopy, a low Na(+)/K(+) ratio was detected in the phloem complex of blade veins in these lower leaves. By transmission electron microscopy, the ultrastructural features were observed in the phloem complex. In the upper leaves of both control and NaCl-treated plants, companion cells in minor veins were found to be transfer cells. These cells may well be involved in the intravenous recycling of ions and in Na(+) flowing out of exporting leaves. Under the effect of NaCl, companion cells in the main veins develop transfer cell features, which may favor the rate of assimilate transport from exporting leaves toward meristems, allowing the positive balance necessary for the survival in salt conditions. These features no longer assist the lower leaves when transfer cells are necrotized in both minor and main veins of NaCl-treated plants. As transfer cells are the only degenerating phloem constituent, our observations emphasize their role in controlling nutrient (in particular, Na(+)) fluxes associated with the stress response.
Databáze: OpenAIRE
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