Mechanism for the detoxification of aluminum in roots of tea plant ( Camellia sinensis (L.) Kuntze)

• Published in: Phytochemistry (Oxford) 2008, Vol.69 (1), p.147-153
• Main Authors: Morita, Akio, Yanagisawa, Osamu, Takatsu, Satoshi, Maeda, Setsuko, Hiradate, Syuntaro
• Format: Article
• Language: English
• Subjects: 27Al-nuclear magnetic resonance; Aluminum; Aluminum - analysis; Aluminum - metabolism; biochemical pathways; Biological and medical sciences; Biotechnology; Camellia sinensis; Camellia sinensis - chemistry; Camellia sinensis - classification; Camellia sinensis - growth & development; Camellia sinensis - metabolism; Chelating Agents - metabolism; chelation; Chemical constitution; Fundamental and applied biological sciences. Psychology; Genetic engineering; Genetic technics; Inactivation, Metabolic; Magnetic Resonance Spectroscopy; metabolic detoxification; Methods. Procedures. Technologies; Oxalate; plant growth; Plant physiology and development; Plant Roots - chemistry; Plant Roots - growth & development; Plant Roots - metabolism; Radioisotopes; root systems; Roots; spectral analysis; Tea plant Camellia sinensis; Theaceae; Transgenic animals and transgenic plants; Transgenic plants; Vacuoles - chemistry; Vacuoles - metabolism
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2007.06.007

The 27Al NMR spectrum of cell sap, extracted from tea root tips, suggested that Al–oxalate complexes were major forms of Al in tea roots. To determine the mechanism of aluminum (Al) detoxification in the roots of tea plants ( Camellia sinensis (L.) Kuntze), the amounts of Al and Al-chelating compounds (fluoride (F), organic acids and catechins) were measured and the chemical forms of Al in root cell extracts were identified by the application of 27Al-nuclear magnetic resonance (NMR) spectroscopy. Tea plants were cultivated in nutrient solutions containing 0, 4, 1.0 and 4.0 mM of Al at pH 4.2 for approximately 10 weeks. The levels of soluble Al, water-soluble oxalate and citrate, but not F, malate or catechins in young roots increased with an increase in the concentration of Al in the treatment solution. The 27Al NMR spectra of root tips and cell sap extracted from root tips that had been treated with Al were almost identical and had four signals, with two (11 and 16 ppm) apparently corresponding to the known chemical shifts of Al–oxalate complexes. In the spectra of cell sap, the resonances at 11 and 16 ppm increased with an increase in the Al contents. These results suggest that the levels of Al–oxalate complexes increased in response to an increase in the Al level, implying that oxalate is a key Al-chelating compound in the mechanism of Al detoxification in the tea root.