Mechanism of Fe uptake by the leaf symplast: Is Fe inactivation in leaf a cause of Fe deficiency chlorosis?

Citation
M. Nikolic et V. Romheld, Mechanism of Fe uptake by the leaf symplast: Is Fe inactivation in leaf a cause of Fe deficiency chlorosis?, PLANT SOIL, 215(2), 1999, pp. 229-237
Citations number
46
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
PLANT AND SOIL
ISSN journal
0032-079X → ACNP
Volume
215
Issue
2
Year of publication
1999
Pages
229 - 237
Database
ISI
SICI code
0032-079X(1999)215:2<229:MOFUBT>2.0.ZU;2-Y
Abstract
The mechanism of iron (Fe) uptake from the leaf apoplast into leaf mesophyl l cells was studied to evaluate the putative Fe inactivation as a possible cause of Fe deficiency chlorosis. For this purpose, sunflower (Helianthus a nnuus L.) and faba bean plants (Vicia faba L.) were precultured with varied Fe and bicarbonate (HCO3-) supply in nutrient solution. After 2-3 weeks pr eculture, Fe-III reduction and Fe-59 uptake by leaf discs were measured in solutions with Fe supplied as citrate or synthetic chelates in darkness. Th e data clearly indicate that Fe-III reduction is a prerequisite for Fe upta ke into leaf cells and that the Fe nutritional status of plants does not af fect either process. In addition, varied supply of Fe and HCO3- to the root medium during preculture had no effect on pH of the xylem sap and leaf apo plastic fluid. A varied pH of the incubation solution had no significant ef fect on Fe-III reduction and Fe uptake by leaf discs in the physiologically relevant pH range of 5.0-6.0 as measured in the apoplastic leaf fluid. It is concluded that Fe inactivation in the leaf apoplast is not a primary cau se of Fe deficiency chlorosis induced by bicarbonate.