ISSN 10227954, Russian Journal of Genetics, 2010, Vol. 46, No. 1, pp. 43–49. © Pleiades Publishing, Inc., 2010.
Original Russian Text © N.V. Melnikova, O.P. Mitrofanova, O.A. Liapounova, A.M. Kudryavtsev, 2010, published in Genetika, 2010, Vol. 46, No. 1, pp. 51–57.
Studies of the crop genetic diversity and the histor
ical and geographical regularities of its formation pro
vide important information, which allows a rational
management of genetic resources in agriculture.
Numerous works have focused on the genetic diversity
of durum wheat, an ancient food crop that is highly
significant for the humanity and has a long cultivation
history. The use of various molecular genetic markers
is the most common and efficient approach. Such
markers have been used to evaluate the durum wheat
cultivars from individual countries, including Italy ,
Canada , and the former Soviet Union , as well
as global genetic diversity of durum wheat [4, 5].
In this work, we used alleles of gliadin, genes cod
ing wheat storage proteins, as convenient genetic
markers. Their analysis is simple and inexpensive, thus
making it possible to examine many accessions from
various regions and to test their withincultivar heter
ogeneity and polymorphism .
Gliadins are a mixture of protein molecules that are
extracted with 60–80% ethanol  and can be sepa
rated electrophoretically . Gliadin synthesis is con
trolled by loci of closely linked genes, which occur on
the short arms of chromosomes of homeology groups
1 and 6 . Genetic analysis has demonstrated that
components of a gliadin electrophoretic pattern are
always inherited as linked groups, or blocks of compo
nent encoded by genes of the same locus. The blocks
display a codominant inheritance, remain stable
through many generations, and are independent of the
growth conditions [10–12]. Multiple alleles have been
identified for each of the four gliadincoding loci of
durum wheat; i.e., blocks controlled by the same locus
in different accessions may vary in the number, elec
trophoretic mobility, and staining intensity of their
components [1, 13].
The objective of this work was to study the genetic
diversity in a collection of tetraploid durum wheat
Desf. accessions for alleles of the glia
MATERIALS AND METHODS
To estimate the global diversity of durum wheat
Desf., we examined 437 cultivars, which had
been developed mostly from the 1940s to the 1980s,
and 28 landraces from 42 countries. Grains were
obtained from the collection of the AllRussian Insti
tute of Plant Industry and Institute of Plant Genetic
Resources (Bulgaria). Eight to one hundred grains
were examined for each accession.
Gliadin was extracted with 70% ethanol; polyacry
lamide gel electrophoresis was carried out by a stan
dard method .
The allelic variants of gliadin component blocks
were identified and designated according to available
catalogs and an accepted system of allele designation
[1, 13, 15].
Genetic diversity for the loci of gliadincoding
genes was estimated according to Nei  as
= 1 –
is Nei’s index of genetic diversity (per
Global Diversity of Durum Wheat
Desf. for Alleles of GliadinCoding Loci
N. V. Melnikova
, O. P. Mitrofanova
, O. A. Liapounova
, and A. M. Kudryavtsev
Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, 119991 Russia;
Vavilov AllRussia Institute of Plant Industry, St. Petersburg, 190000 Russia
Received June 2, 2009
—Genetic diversity for the alleles of gliadincoding loci was studied with 465 durum wheat acces
sions from 42 countries. A total of 108 alleles were identified for four loci; 60 alleles were described for the
first time. Broad diversity of rare gliadincoding alleles was observed. The highest genetic diversity was char
acteristic of durum wheat accessions from the Middle East, TransCaucasia, the Pyrenean Peninsula, and the
Balkans. Two genetically isolated ancient branches of durum wheat were isolated. A “southern” branch
included mostly accessions from the Mediterranean region, the Middle East, and TransCaucasia. A “north
ern” branch included Russian and Ukrainian durum wheat accessions and varieties obtained on their basis.
An additional group included durum wheat accessions that had been obtained in several past decades on the
basis of the material of international breeding centers (CIMMYT and ICARDA) and had low genetic diver