Peroxidase complex with concomitant anodal and cathodal variation in red-fruited tomato species.

Four groups of bands (a-d) are controlled by 19 alleles of the Peroxidase-4 (Prx-4) complex in the red-fruited tomato species, Lycopersicon esculentum and L. pimpinellifolium. Heterozygotes can be detected by virtue of codominance in all combinations except a few in which bands of single groups are absent ("semi-null" alleles). No recombinations were detected in 7419 F(2) segregants of 53 different combinations of alleles. A maximum fiducial limit (P = 0.01) of 0.08% crossing-over between any Prx-4 band groups is estimated. Variation of the anodal b bands is absolutely associated with that of the cathodal d band in respect to presence versus absence and direction of migration. In respect to the origin of these variants, the probability of 18 instances of simultaneous mutation of genes at two loci, always in such complete agreement, is so remote that no more than one locus could conceivably govern b and d. The disposition of a is not similarly associated with that of the other bands, while that of the faint-staining c could not always be reliably resolved. The negation of all save extremely low recombination rates and the observed concomitant variation of b and d strongly support the concept of single locus control of all Prx-4 banding, this hypothesis being espoused until rejection should be required be required by future research. Models of single locus control of several isozymes are discussed.