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          Institute: MPI für Evolutionsbiologie     Collection: Tropical ecology     Display Documents

ID: 61123.0, MPI für Evolutionsbiologie / Tropical ecology
Iron distribution in three central Amazon tree species from whitewater-inundation areas (várzea) subjected to different iron regimes
Authors:De Simone, Oliviero; Müller, Ewald; Junk, Wolfgang J.; Richau, Kerstin; Schmidt, Wolfgang
Date of Publication (YYYY-MM-DD):2003-11
Title of Journal:Trees
Issue / Number:6
Start Page:535
End Page:541
Review Status:Peer-review
Audience:Not Specified
Abstract / Description:Trees inhabiting central Amazon floodplain forests are subjected to an annual flood-pulse lasting up to 10 months, leading to both oxygen shortage and accumulation of high levels of reduced iron. To understand the mechanisms underlying the adaptation to these conditions, cuttings from three tree species typical of várzea inundation forests ( Salix martiana, Tabernaemontana juruana, and Laetia corymbulosa), were cultivated either aerobically or anaerobically under different iron regimes in greenhouse experiments. Although all species are considered to be non-deciduous, Laetia corymbulosa lost and formed new leaves continuously during the experimental period. Although relative growth rates (RGRs) of all species declined in response to hypoxic conditions, no marked changes in RGRs were apparent among different iron concentrations in the growth medium, ranging from 50 to 500 µM, supplied in ferrous form as FeSO 4. Whereas roots exhibited color changes due to the formation of iron precipitates, no visual symptoms of iron toxicity were observed in the leaves. Iron concentration increased in all organs of all species with increasing iron concentrations in the medium, except for leaves of S. martiana and T. juruana, suggesting an effective restriction of iron influx into the leaf symplast. Although the leaf iron concentration was at the upper limit of the critical range at high external iron levels, it is suggested that internal active transport rather than intracellular detoxification mechanisms contribute to the tolerance to supra-optimal iron levels. Anatomical traits such as suberization of peripheral cell walls and the formation of aerenchyma appear to be of minor importance for Fe tolerance.
Free Keywords:Iron; Iron tolerance; Flooding, Radial oxygen loss; Aerenchyma
External Publication Status:published
Document Type:Article
Communicated by:Pia Parolin
Affiliations:MPI für Limnologie/AG Tropenökologie
External Affiliations:Department of Biology, University of Oldenburg, P.O.Box 2503, 26111 Oldenburg, Germany; Humboldt University Berlin, Institute of Biology, Applied Botany, Invalidenstrasse 42, 10115 Berlin, Germany
LOCALID:2244/S 38068 [Listen-Nummer/S-Nummer]
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