© 2004 Heron Publishing—Victoria, Canada
Effects of aluminum on organic acid metabolism and secretion by red spruce cell suspension cultures and the reversal of Al
effects on growth and polyamine metabolism by exogenous organic acids
Rakesh Minocha (1, 2) and Stephanie Long (1)
1. USDA Forest Service, Northeastern Research Station, P.O. Box 640, 271 Mast Road, Durham, NH 03824, USA / Author to whom correspondence should be addressed (rminocha@hopper.unh.edu) / Received November 28, 2002; accepted January 29, 2003; published online December 1, 2003
Summary
In the absence of added Al, the concentration of succinate in cultured red spruce (Picea rubens Sarg.) cells was 15–20 times higher (> 600 nmol gFW-1) than that of citrate or oxalate and 4–6 times higher than that of malate. Addition of AlCl3 (effective monomeric Al concentrations of 0.23 and 0.48 mM) to 3-day-old suspension cultures significantly increased cellular
succinate concentrations with a concomitant decrease in cellular oxalate concentrations. However, in the medium of Al-treated
cell cultures, both succinate and oxalate concentrations were significantly higher than in the medium of cell cultures without
added Al, and oxalate concentrations were several times higher than succinate concentrations. Aluminum did not significantly
affect the cellular concentrations of malate, ascorbate and citrate, and none of these organic acids was present in detectable
quantities in the medium. Exogenous succinate alone or with Al had no effect on cellular free polyamine concentrations or
cell mass. Aluminum caused a significant increase in cellular putrescine concentrations. Addition of malate had a positive
effect on growth and completely reversed the effects of Al on cell physiology. In contrast, the addition of oxalate and citrate
only partly reversed the effects of Al.
Keywords:
citrate, inorganic ions, malate, oxalate, phosphorus, putrescine, succinate.
