Genetic analysis of mannose-6-phosphate isomerase in soybeans
Five mannose-6-phosphate isomerase (EC 5.3.1.8) variants were observed electrophoretically in cultivated soybeans (Glycine max (L.) Merr.) and wild soybeans (G. soja Sieb. &Zucc.). Four of the five variants differed in the mobility of the two mannose-6-phosphate isomerase bands observed, while the fifth showed no enzyme activity. Several crosses involving different variants were made to study inheritance of the observed variants. The inheritance data showed that the five variants were allelic and controlled by a single locus (Mpi). The five alleles were as follows: Mpi-a (Rf 0.61 and 0.66); Mpi-b (Rf 0.66 and 0.7); Mpi-c (Rf 0.71 and 0.75); Mpi-d (Rf 0.76 and 0.80); and mpi. Mpi-a, Mpi-b, Mpi-c, and Mpi-d are codominant, and the null allele mpi is recessive. The Mpi-b allele is most common while the Mpi-d and mpi alleles are rare in both the cultivated and wild soybean germ plasm from various sources examined.Key words: Glycine max, Glycine soja, isozymes, Mpi, gel electrophoresis, allelic frequency.