Plasma membrane lipids are the powerful components for early stage aluminum tolerance in triticale

The order of aluminum (Al) tolerance in triticale lines (ST2 > ST22) after re-elongation in an Al-free 0.2 mm calcium (Ca) solution for 9 h (Ca period) following I h pretreatment with 20 mu m Al (Al period) agreed with that after 24 h of Al treatment. Permeability of the plasma membrane (PM) of root-tip cells after the Ca period was significantly increased in Al-sensitive ST22. Al was accumulated more heavily in the root-tip portion of ST22 than in that of ST2, although similar amounts of malic and citric acid anions were released from both triticale lines. We established a new system examining lipid permeability using synthesized nylon-2,8 ultrathin and porous capsules trapped previously with 0.1% (w/v) methylene blue solution and coated thereafter with PM lipid isolated from root tips by a newly developed technique. Permeability of the PM lipid measured with time in 0.2 mm Ca with or without 50 mu m Al photometrically (A(680)) was significantly greater in M-sensitive ST22 after 5 min of Al treatment. This is the first report to directly show the primary and early role of PM lipid in Al tolerance in triticale.