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

Abstract

Four groups of bands (a-d) are controlled by 19 alleles of the Peroxidase4 (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 F2 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 banding, this hypothesis being espoused until rejection should be required by future research. Models of single locus control of several isozymes are discussed.The peroxidases of tomato species present an unusually rich assortment of isozymes (1-4). At least six, possibly more, loci govern the banding patterns detected by starch-gel electrophoresis. Amongst these isozymes, a group that we designate Prx-4 (fourth from the anodal front; Fig. 1) displays the greatest diversity of genetic variants and greatest complexity of phenotypic expression. To simplify presentation of the data, it is assumed here that all activity in this complex is governed by alleles at the single Prx-4 locus-a point that will be considered further in the discussion. This article deals solely with expression of Prx-4 phenotypes and their inheritance in the red-fruited species, Lycopersicon esculentum Mill. and L. pimpinellifolium (Jusl.) Mill. Their distribution in the ranges of these two species and evolutionary significance will be treated in subsequent publications.The complexity of phenotypic expression at Prx-4 permits the recognition of many different allozymes coded by multiple alleles of this locus. Our approach to the recognition and designation of alleles is conservative; none are thus recognized until their distinctness is unequivocally proven. The acid test of distinctness is not repeated comparisons between various lines of presumed variants, as assumed by many investigators, but F2 segregations in crosses between them. In F2 populations, the parental homozygous types and their heterozygote can be contrasted. If segregation of the three genotypes (or two in cases of complete dominance) cannot be discerned, the putative alleles do not warrant recognition.For the following reasons, our survey probably does n...

Genetic variation in natural populations of wild barley (Hordeum spontaneum)

“…Ahhough fifteen alleles were identified, the data of Allard et al (1971) indicate that this is only a fraction of the total alleles at this locus in the wild and cultivated barley species as a whole. Polyallelic loci in plants are already known for a peroxidase locus in wild and cultivated tomato species (Rick & Fobes, 1976), and ~3-glucosidase in maize (Stuber et al, 1977). The main (most conspicuous) band determined by each allele of the Est-2 complex showed an alteration in the order of mobility in the two different buffer systems.…”

Ενζυμικές Δράσεις Στις Ελιές Και Το Ελαιόλαδο

“…Η σύνθεση της γίνεται πιθανώς στο ενδοπλασματικό δίκτυο, η τροποποίηση της στα όργανα του Golgi, απ' όπου και εκκρίνεται με ίδιο τρόπο με τις άλλες γλυκοπρωτεΐνες (Hu & Huystee 1989), είναι δε περισσότερο δραστική στα κυτταρικά τοιχώματα (Kim et al 1989a). Απαντάται σε φυτά , όπως τα ραδίκια, ο ανανάς, τα σύκα, οι πατάτες, οι ντομάτες, ο καπνός, το αράπικο φυστίκι, το λινάρι, τα φασόλια, οι φράουλες και τα λαχανικά (Novacky & Hampton 1968, Hart et al 1971, Rick & Fobes 1976, Pütter & Becker 1983, Hu & Huystee 1989, Lopez-Serrano & Barceló 1997. Η μοριακή της μάζα κυμαίνεται μεταξύ 31 και 33 kDa (Mazza & Welindeer 1980, Lagrimini et al 1987, Hu & Huystee 1989.…”