Four Peroxidase Loci in Red-Fruited Tomato Species: Genetics and Geographic Distribution

Abstract

The banding patterns of certain anodal peroxidase variants of red-fruited tomato species are governed by alleles at four loci-two alleles per locus. Alleles at three loci code for modified enzyme migration patterns and are codominant in heterozygotes; those at the fourth locus code for presence or absence of a band. No evidence of linkage was detected in preliminary tests between four of the six possible combinations of loci. All variant alleles-i.e., those not represented in the standard genotype of Lycopersicon esculentum-exist in the wild L. pimpinellifolium from coastal Peru; all but Prx-3" are also known in L. esculentum from the sympatric region but are rare or absent elsewhere. Between the distributions of alleles of Prx-1 and those of Ge, the gamete-eliminator locus, a significant association exists, which probably does not owe to genetic linkage. The tendency of alleles of Prx loci, as well as those of cm, Ge, h, and Od, to be shared between wild and cultivated taxa in the sympatric region but seldom elsewhere, in addition to published correlated evidence, suggests that the wild alleles tend to substitute in cultivated forms as a result of introgression. In respect to the number of common alleles, cultivated tomatoes more closely resemble the wild L. esculentum var. cerasiforme than L. pimpineUifolium.The analysis of allozymic polymorphisms in higher plants by means of gel electrophoresis has greatly expedited research in population genetics and has provided a tool useful for tracing phylogenetic relationships. The many applications of the latter type have been reviewed recently (1).Many mutations affecting gross morphology are known in the cultivated tomato, Lycopersicon esculentum Mill., (esc), and the very closely allied L. pimpinellifolium (Jusl.) Mill., (pim), yet none characterize these species or their subspecific taxa and few assist in tracing phylogenies. Such variant alleles as c, f, r, and y are found in wild forms and in cultivars, but their sporadic appearance has little or no phylogenetic significance. For this reason we initiated a search for allozymes in the tomato species.Marked quantitative differences in certain peroxidases were found to be associated with the dX mutant (2), but qualitative differences were not found.

Construction and Some Characterization of a Yeast Artificial Chromosome Library from DNA of a Tomato Line Having Four Disease Resistance Traits

“…4) We have described the isolation of an Aps-P-specific DNA fragment by PCR. 5 ) We report here the construction and some characterization of a Y AC library of a nematode-resistant tomato line (Lycopersicon esculentum Mill.…”

Allozymes of Galapagos Tomatoes: Polymorphism, Geographic Distribution, and Affinities

“…Est-L", which is universal in L. cheesmanii, is widespread in both coastal regions. Prx-L'; present in all tested f. minor and the majority of other forms of L. cheesmanii, is found in nearly all the Peruvian material but is not known in the Ecuadorian collections (Rick et al, 1974). Prx-7 characteristic of most of the San Salvador region, is common in Ecuadorian accessions, but is also known as a rare variant in northern Peru.…”

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

“…Sources of the Prx-41 allele are listed in ref. 4, those for other alleles in L. esculentum in ref. 2, whilst those for L. pimpinellifolium will be listed with other pertinent collection data in an article now in preparation dealing with geographic distribution of alleles and evolution of that species.…”

“…The peroxidases of tomato species present an unusually rich assortment of isozymes (1)(2)(3)(4). At least six, possibly more, loci govern the banding patterns detected by starch-gel electrophoresis.…”