Proceedings of the XLV Italian Society of Agricultural Genetics - SIGA Annual Congress

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

EVALUATION OF POLYPHENOL OXIDASE ACTIVITY IN TETRAPLOID WHEATS

SIMEONE R.*, PASQUALONE A.**, CLODOVEO M.L.*, BLANCO A.*

* Dipartimento di Biologia e Chimica Agro-Forestale ed Ambientale, Università di Bari, Via Amendola, 165/A, 70126 Bari

** Dipartimento di Progettazione e Gestione dei Sistemi Agro-Zootecnici e Forestali, Università di Bari, Via Amendola, 165/A, 70126 Bari

polyphenol oxidase, protein content, tetraploid wheat, variability

Pasta colour is an essential factor in assessing pasta quality. It results from a desirable yellow component, an undesiderable brown component and, under some drying conditions, a red component. Brown colour depends on enzymatic and chemical factors. The enzymatic browning is due to the activity of the polyphenol oxidase (E.C. 1.14.18.1) that is mainly localised in the peripheral part of wheat kernel. Polyphenol oxidase is involved in the oxidation of endogenous wheat phenolic compounds resulting in the production of highly coloured products. Milling to high extraction yields may significantly raise the content of polyphenol oxidase thus negatively affecting the colour of the end-products. Besides, it is known that protein content of wheat affects pasta brownness so that for a given cultivar an increase of protein content results in higher brownness.

An evaluation of polyphenol oxidase activity among a set of durum wheat (Triticum turgidum var. durum) Italian cultivars and wild accessions of Triticum turgidum var. dicoccoides and var. dicoccum was done. The method used was based on a spectrophotometric measure indicating the oxidation level of a tyrosine solution where kernels were incubated. Values found ranged from 0.85 to 2.39 with higher values in some wild accessions of var. dicoccoides. The purpose was to assess the genetic variability of the character as well as to individuate plant materials characterised by extremely different polyphenol oxidase activity values to use them to constitute a segregating mapping population. This, to individuate loci for polyphenol oxidase activity that are independent from protein content.