8th INTERNATIONAL WHEAT CONFERENCE

VARIABILITy IN gRAIN quALITy ChARACTeRISTICS
ANd gLuTeNIN SuBuNIT ComPoSITIoN of duRum
WheAT LANdRACeS fRom The medITeRRANeAN BASIN
Roberto J. Peña 1 , Dolors Villegas 2 , Ruyman Nazco 2 ,
Karim Ammar 1 , Jose Crossa 1 , Conxita Royo 2
1 International Maize and Wheat Improvement Center (CIMMYT), Apdo. Postal 6-641,
06600, Mexico DF, Mexico
2 IRTA, Cereal Breeding, IRTA, Rovira Roure, 191, 25198 Lleida, Spain
E-mail address of presenting author: j.crossa@cgiar.org
Durum wheat is an especially important cereal crop around the Mediterranean basin,
providing the preferred raw grain for a wide range of staples foods. Since the late 60s,
most of the local varieties and numerous landrace types have been displaced by the higher
yielding, improved semi-dwarfs. Characterizing a representative number of Mediterranean
landraces can help identifying unused or under-used sources of variability for
traits important to industrial processing quality. In the present study, 173 genotypes from
23 countries were evaluated for quality attributes during 3 crop cycles (2007, 2008, 2009)
at Lleida-Spain, using an unreplicated design with replicated checks. The genotypes included
head-row purified lines from 155 landraces and 18 modern cultivars grown in
the region. They were evaluated for thousand kernel weight, test weight, protein content,
gluten strength (SDS-sedimentation volume), yellow color (concentration of yellow pigments
in the grain) and a Quality Index was determined through a formula integrating
all these parameters. In addition, each genotype was characterized by SDS-PAGE for its
high and low molecular weight glutenin subunit composition at 5 loci, namely Glu-A1,
Glu-B1, Glu-A3, Glu-B3, and Glu-B2. The landrace types were characterized by higher
average kernel weight (with a wider range of values) and slightly lower average test weight
than the modern cultivars, suggesting that the use of landraces as sources of increased
grain size should be accompanied by cautious selection for acceptable test weight. In
spite of significantly higher average protein content, the landraces exhibited substantially
lower average gluten strength than modern cultivars. Also, modern cultivars showed a
significantly higher average pigment concentration in their grain than landraces. Logically,
this resulted in an average quality index higher for modern cultivars. However, it
is important to note that a good number of landraces (36%) were at least as good as the
best modern cultivars in terms of their integrated quality index, which would make them
viable, from a quality stand-point, in part of the European market. These landraces with
overall suitable quality were from 17 of the 23 countries represented, including the major
durum producers/users. Landraces with the highest pigment concentration (comparable
to that of modern cultivars) tended to originate from the northern shore of the Mediterranean
(frequently from Spain), and the Middle East (frequently, Jordan). However, none
could be considered as sources of especially high pigment concentration, and their use
in breeding would be dependent on whether or not they possess novel alleles that could
interact with or replace favorably those present in modern germplasm (not addressed in
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