Genetic mapping of polyphenol oxidase in tetraploid wheat

Pasta colour is one of the main factors influencing pasta quality. It is the product of a desirable yellow component, an undesirable brown component and, under some drying conditions, a red component. The brown colour depends on enzymatic and chemical factors. Polyphenol oxidase (PPO; E.C. 1.14.18.1) is one of the enzymatic factors. It is mainly localised in the peripheral part of the wheat kernel, and is involved in the oxidation of endogenous wheat phenolic compounds resulting in the production of highly coloured products. Therefore, a knowledge of the genetic control of PPO activity could enable the developing of better strategies in breeding programs to reduce pasta darkening. The aim of this study was to map the gene(s) affecting PPO activity using a set of recombinant inbred (RI) lines, derived from a cross between Triticum turgidum L. var. durum cultivar Messapia and the accession MG4343 of Triticum turgidum L. var. dicoccoides. After performing linkage analysis, the gene for high PPO activity was mapped on the long arm of the chromosome 2A and its characteristic was found highly associated to the RFLP marker Xutv1427-2A, with a value of LOD equal to 29.84. The identification of molecular markers linked to loci controlling the PPO activity may potentially accelerate wheat breeding since the selection of plants can be carried out by genotype rather than phenotype.