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

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 2.40

FINE MAPPING OF HIGH PROTEIN CONTENT QTLs IN DURUM WHEAT

A. GADALETA, A. SIGNORILE, A. BLANCO

Department of Environmental and Agro-Forestry Biology and Chemistry, University of Bari, Via Amendola 165/A, 70126 Bari, Italy

protein content, QTLs, durum wheat, microsatellite, AFLP

The lack of sufficient genetic variation for useful traits within the cultivated wheats has limited the ability of plant breeders to improve grain yield and grain quality. A good source of genetic variation has been found in wild wheats and related species. The wild tetraploid wheat Triticum turgidum ssp. dicoccoides shows particular promise as a donor of useful genetic variation for several traits, including grain protein quality and quantity.

The development of molecular markers and maps, and the recent strategies for molecular breeding, referred to as advanced backcross QTL (AB-QTL) analysis, have shown that the backcrossing method has considerable potential for the genetic analyses of quantitative traits and as a method of breeding higher yielding and quality crop varieties.

The objective of the present study was the fine mapping of three high protein content QTLs introgressed from var. dicoccoides into durum wheat cultivar Latino by the backcross inbred line (BIL) method.

Three markers (Xgwm275-2A, Xgwm577-7B, P39M37₍₂₅₀₎-6A), located on chromosome 2A, 6A, 7B, were previously found to be associated to loci for high protein content. Microsatellites and AFLP markers and the “bulked segregant analysis” were used for the saturation of these 3 regions. Such markers were considered potentially linked to QTL for protein content and then screened on the complete population of 144 F3 progenies. The putative linkage of these markers with protein content QTLs was confirmed by regression analysis of each marker locus on the F2, F3 and F4 populations (3BIL-85, with high protein content, backcrossed to Latino with low protein content).

Mapping loci by backcross inbred lines should enable the obtaining of near-isogenic lines (NILs) in which the individual effects of each QTL can be examined in detail without confounding variation due to other putative QTLs. These near-isogenic lines could also be useful to conduct physiological studies aimed at investigating the potential mechanisms leading to high protein content, to fine-map the position of each QTL, and eventually to map-based cloning.

The relatively low heritability of quantitative traits makes it difficult to select for useful alleles from wild germplasm based on phenotypic evaluation of single plants and/or in single environments so the detection of molecular markers tightly linked to quantitative trait loci is useful for the marker assisted selection in wheat breeding programs.