Inheritance of leaf peroxidase isoenzymes in Nicotiana alata and linkage with the S-incompatibility locus

Genetic analysis of peroxidase isoenzymes observed by electrophoresis shows that each of the two cathodic bands are controlled by one gene, respectively, PI and PII. Each gene has two allele forms; presence of activity (dominant) and absence of activity (recessive). The same situation is found for one anodic band; the three other anodic bands are controlled by a single gene with three active allele forms. No progenies seem to be produced from gametes P I (-) P II (-) (no activity of PI or PII). Investigation of the incompatibility system and the isoperoxidases demonstrates that the loci PI, PII and S are located in the same chromosome. PI is closely linked to the S locus (3 cM); the distance between PII and the S locus is 34 cM.