Genetics of the peroxidase isoenzymes in Petunia

Summary By starch gel electrophoresis three mobility variants of a cathodic moving doublet of bands, encoded by the structural gene prxC, were detected in all organs of flowering petunias. In root tissue two of the variants showed a lower electrophoretic mobility than in other organs. During development of flower buds the PRXc enzymes showed an increase in mobility. The gene prxC was located on chromosome IV by showing linkage to the genes An3 and Dw1, by trisomic segregation, and by the construction of triply heterozygous trisomics IV. The gene order on chromosome IV is B1-An3/Dw1-prxC. It was concluded that the temporal programming difference in the expression of the alleles prxC2 and prxC3 is caused by internal site mutation. Analysis of progeny obtained by crossing of lines to the trisomic IV with genotype prxC1/C1/C2 showed differential expression of the two prxC1 alleles of the trisomic IV.