XVI International Botanical Congess

Measurement of Al transport across bio-membranes is hampered by the complex chemistry of Al, its tight binding to the cell wall, and a lack of sensitive analytical techniques. We measured transport in single cells of C. corallina using the rare 26Al isotope, accelerator mass spectrometry and a protocol for surgical isolation of subcellular fractions. While accumulation of Al in the cell wall dominates total uptake (>99%), entry into the protoplasm is detected within 30 min. Transport across the tonoplast is negligible at first, but accelerates to rates similar to uptake across the plasma membrane. Accumulation in the wall and protoplasm reflect changes in {Al3+}brought about by changing Al supply, complexing ligands, and solution pH. Our use of 26Al-AMS in this system provides unique insight into the nature of Al transport across biological membranes.