16 Aluminum Soils contain an average of 7% total aluminum (Al), and under acidic conditions, aluminum is solubilized (1), increasing availability to plants and aquatic animals. Soil acidification due to application of fertilizers, growing of legumes. | 7 24 2006 7 23 PM Page 437 Section IV Beneficial Elements 7 24 2006 7 23 PM Page 438 7 24 2006 7 23 PM Page 439 16 Aluminum Susan C. Miyasaka Hue and Michael A. Dunn University of Hawaii-Manoa Honolulu Hawaii CONTENTS Introduction .441 Aluminum-Accumulating Plants .441 Beneficial Effects of Aluminum in Plants .442 Growth Stimulation .442 Inhibition of Plant Aluminum Absorption and Transport within Plants .442 Phytotoxic Species .442 Absorption .443 Aluminum Speciation in Symplasm .443 Radial Aluminum Toxicity Symptoms in Plants .444 Short-Term Effects .444 Inhibition of Root Elongation .444 Disruption of Root Cap Processes .444 Callose Formation .445 Lignin Deposition .445 Decline in Cell Division .445 Long-Term Effects .445 Suppressed Root and Shoot Biomass .445 Abnormal Root Morphology .446 Suppressed Nutrient Uptake and Translocation .446 Restricted Water Uptake and Transport .446 Suppressed Photosynthesis .446 Inhibition of Symbiosis with Rhizobia .447 Mechanisms of Aluminum Toxicity in Plants .447 Cell Modification of Synthesis or Deposition of Polysaccharides .448 Plasma Membrane .448 Binding to Phospholipids .448 Interference with Proteins Involved in Transport .449 H -ATPases .449 Potassium Channels .449 Calcium Channels .450 Magnesium Transporters .450 .
