Genetic control of acid phosphatase Rm and its relation to control of peroxidase Rm in flax (Linum) genotrophs.

Evidence from various workers has indicated that isozyme relative mobility (Rm) may not be defined solely by the corresponding structural gene but may also be modified by alleles at other loci. The instances of numerous, small ongoing temporal or tissue changes in Rm for certain enzyme systems in plants may be another aspect of this modification due to interactions between genes. A further possible example of Rm modification occurs in connection with environmentally (fertilizer treatment) induced heritable changes within particular completely inbred and genetically homogeneous plant genotypes. Fertilizer-induced, persistent relative mobility (Rm) shifts for peroxidases are controlled by two alleles at one locus, a dominant for faster Rm and a recessive for slower Rm; codominance is completely absent. There are similar Rm shifts in acid phosphatases, likewise stemming from molecular weight changes. This study examined genetic control of the acid phosphatase Rm shift and its relation to peroxidase Rm control. It showed that the environmentally induced heritable acid phosphatase Rm shift is controlled by an identical system of a dominant (faster) and recessive (slower) allele, closely linked to the locus controlling peroxidases. The Rm shifts for both these enzyme glycoproteins are unidirectional, with no codominance; at least 10 other nonidentified glycoproteins display the same unidirectional Rm shifts. The results suggest modification, possibly posttranslational or transcriptional, controlled by modifier loci. This supports indications in other organisms that small numbers of modifier loci may control widespread Rm changes in the protein products of a genome.