title: Aluminium toxicity in rye (Secale cereale): root growth and dynamics of cytoplasmic Ca2+ in intact root tips.
abstract: Aluminium (Al) toxicity in rye (Secale cereale L.), an Al-resistant crop, was examined by measuring root elongation and cytoplasmic free activity of calcium ([Ca2+]cyt) in intact root apical cells. Measurement of [Ca2+]cyt, was achieved by loading a Ca2+-sensitive fluorescent probe. Fluo-3/AM ester, into root apical cells followed by detection of intracellular fluorescence using a confocal laser scanning microscope. After 20 min of exposure to 50 microM Al (pH 4-2) a slight increase in [Ca2+]cyt of root apical cells was observed, while the response of [Ca2+]cyt to 100 microM Al (pH 4.2) was faster and larger ([Ca2+]cyt increased by 46% in 10 min). Increases in [Ca2+]cyt were correlated with inhibition of root growth, generally measurable after 2 h. Addition of 400 microM malic acid (pH 4.2) largely ameliorated the effect of 100 microM Al on [Ca2+]cyt in root apical cells and protected root growth from Al toxicity. These results suggest that an increase in [Ca2+]cyt in root apical cells in rye is an early effect of Al toxicity and is followed by the secondary effect on root elongation.
authors.affiliation: Soil Science and Plant Nutrition, University of Western Australia, Crawley, Australia.
authors.forename: M A
authors.initials: MA
authors.lastname: Qifu
authors.forename: Zdenko
authors.initials: Z
authors.lastname: Rengel
authors.forename: John
authors.initials: J
authors.lastname: Kuo
mesh_terms: D000535:Aluminum / Q000008:administration & dosage / Q000633:toxicity*; D000814:Aniline Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008293:Malates / Q000494:pharmacology; D018613:Microscopy, Confocal; D018518:Plant Root Cap / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D012434:Secale / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D014966:Xanthenes / Q000494:pharmacology
chemical_list: D000814:Aniline Compounds; D008293:Malates; D014966:Xanthenes; C059715:Fluo-3; C030298:malic acid; D000535:Aluminum; D002118:Calcium