Functional Plant Biology Functional Plant Biology Society
Plant function and evolutionary biology

Aluminium induces an increase in cytoplasmic calcium in intact wheat root apical cells

W.-H. Zhang and Z. Rengel

Australian Journal of Plant Physiology 26(5) 401 - 409
Published: 1999


Disturbance of cytoplasmic Ca 2+ homeostasis, leading to breakdown in Ca 2+ -mediated signal transduction processes, has been suggested as a primary mechanism of aluminium (Al) rhizotoxicity in plants. To test this hypothesis, Al-related changes in cytoplasmic free activity of Ca 2+ ions ([Ca 2+ ] c ) in root apical cells of near-isogenic wheat (Triticum aestivum L.) lines differing in Al tolerance at a single locus were examined by visualising the Ca 2+ -sensitive probe Fluo-3 with confocal laser scanning microscopy. Exposure of roots to 50 µM AlCl 3 (pH 4.2) led to an increase in [Ca 2+ ] c of root apical cells in both Al-sensitive (ES8) and Al-tolerant (ET8) wheat lines. An increase in [Ca 2+ ] c was greater in ES8 than in ET8; after 1-h treatment with 50 µM AlCl 3 an increase in [Ca 2+ ] c was 48 and 27 % in ET8 and ES8, respectively. An increase in [Ca 2+ ] c of ES8 roots, but not ET8 roots, was observed upon treatment with 2.6 µM AlCl 3 (pH 4.5). Al-related increases in [Ca 2+ ] c were correlated with inhibition of root growth. The Al-induced increase in the [Ca 2+ ] c was reversible upon removing AlCl 3 . These findings provide direct evidence to support the hypothesis that Al interactions with cytoplasmic Ca 2+ are involved in the Al toxicity syndrome in plants.

Keywords: Triticum aestivum, cytosolic calcium, secondary messengers, rhizotoxicity, roots.

© CSIRO 1999

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