Genetic control of alcohol dehydrogenase, malate dehydrogenase, and phosphoglucomutase isozymes in lima bean (Phaseolus lunatus L)

A suitable electrophoretic separation method for alcohol dehydrogenase (ADH), malate dehydrogenase (MDH), and phosphoglucomutase (PGM) from P. lunatus has been developed. Two loci (Adh-2 and Pgm-2) showed codominant inheritance and fitted Mendelian ratio. ADH isozyme banding patterns indicate a dimeric quaternary structure, while those of PGM were in agreement with a monomeric nature. The cytoplasmic location of two MDH isozymes (Mdh-1 and Mdh-2) selectively inactivated by homogenization in an ascorbic acid solution was demonstrated. However, distorted ratios were observed for Mdh-2 segregation. On the basis of MDH isozyme banding patterns observed in five progeny families, it is suggested that this enzyme system is a dimeric protein encoded by at least three codominant genes (Mdh-1, Mdh-2, and Mdh-3). Joint segregation tests between pairs of segregating loci (Adh-2, Mdh-2, and Pgm-2) indicated that each of them is inherited independently.