Malate dehydrogenase isozymes in flax genotroph leaves: differences in apparent molecular weight and charge between and within L and S.

Ferguson plots demonstrated that corresponding malate dehydrogenase (MDH) isozymes of Durrant's L and S flax genotrophs differ in apparent molecular weight (MW) and also in net negative charge. The MW differences explain heritable differences in electrophoretic relative mobility (Rm) between corresponding L and S isozymes. The MW for each MDH isozyme was higher for L than for S and resulted in a slower Rm for L. The net negative charge for each isozyme was higher for L than for S. MDH isozymes also differ in MW within L and S. MW was lower for isozymes in leaves from the bottom of the stem than in leaves from the top of the stem, particularly in L. Integration of information on the MDH isozyme system in the flax genotrophs and information on the peroxidase system suggests the possibility that common modifier loci may control Rm in both enzymes.