1022-7954/05/4108- © 2005 Pleiades Publishing, Inc.
Russian Journal of Genetics, Vol. 41, No. 8, 2005, pp. 823–834. Translated from Genetika, Vol. 41, No. 8, 2005, pp. 1013–1026.
Original Russian Text Copyright © 2005 by Zlatska.
During the past 50 years, considerable advances
have been made in the improvement of common wheat
by breeding. The potential grain yield has increased by
almost 90% during this period . Signiﬁcant positive
results have been obtained in breeding by grain quality
traits (grain size, sedimentation parameters, technolog-
ical properties of dough) and plant resistance to some
biotic and abiotic environmental factors. Yet, no
progress has been achieved in improving the character
of grain protein content. At best, this parameter
remained constant. However, the prevailing trend was a
reduction in grain protein content [2–5]. According to
Avivi (cited in ), the level of global protein yield in
wheat did not change during three decades (1949–
1979), despite an increase in productivity of this crop.
To clarify this situation, a critical estimation of the
results of studying the character of grain protein con-
tent is needed as well as guidelines for its further inves-
tigation and possible improvement in common wheat.
This is the main aim of the present article.
GENETIC STUDIES OF THE GRAIN
The history of investigating grain protein content
(GPC) dates back to 1926, when the American
researcher Clark has shown that the variation of this
character is continuous, as in other measurable, or
quantitative, traits . The history of genetic investiga-
tion of GPC has completely repeated that of other quan-
titative characters. Depending on the material exam-
ined, the method of trait assessment, and the procedure
of treatment of the results, different conclusions were
made: the number of genes were estimated as one or
many , while the heritability coefﬁcient varied in the
range from 0.25 to 0.70 [8–12]. In most studies, the
character was considered polygenic, although some
authors argues that it was controlled by a small number of
major genes and several modiﬁer genes. A low grain con-
tent is inherited as a dominant or partially dominant char-
acter; in some cases, transgressive segregation was
reported [9, 11, 12–14]. It was noted that grain protein
content was controlled by regulatory genes rather than by
genes coding for storage proteins .
Historically speaking, the interest in this character
has experienced ups and downs. An appearance of
novel plant material, development of new methods of
the trait assessment, new mathematical models for
genetic analysis, and molecular genetic models for
plant investigation resulted in a sharp burst in the num-
ber of works in this area. In what follows, I consider
some stages that had greatest impact on the develop-
ment of views on GPC genetic control in more detail.
Establishing correlations between GPC and other
characters as well as biotic and abiotic factors
of the ﬁrst targeted stages of investigation of this char-
acter. Very early, it has been shown that GPC, like other
quantitative characters, is signiﬁcantly affected by
environmental conditions: precipitation and tempera-
ture at grain maturation, irrigation conditions, and the
presence of nutrients [15–25]. Johnson
have concluded that only 5% of the character variation
is explained by genotype, while the remaining variation
is accounted for by growth conditions or genotype–
environment interactions. Stuber
 have shown
that differences in grain protein content occurs not only
among the plants within a population, but also among
different grains within an ear.
Furthermore, other correlations has been estab-
lished: spring wheats overperform winter wheat in gen-
eral protein content, and tetraploid wheats contain more
protein than hexaploids ; under the same growing
Grain Protein Content in Wheat: Genetics of the Character
and Some Predictions for Its Improvement in Common Wheat
A. V. Zlatska
Institute of Plant Physiology and Genetics, National Academy of Sciences of Ukraine, Kiev, 03022 Ukraine;
fax: (38-044) 257-51-50; e-mail: firstname.lastname@example.org
Received September 24, 2004
—The results of studies on genetic control of the grain protein content in common wheat and the
attempts of its improvement using traditional breeding approaches and methods of experimental mutagenesis
and introgressive hybridization are presented. The evolution of the views on the genetic structure of the char-
acter is considered. Possible explanations are given to the fact that the attempts to signiﬁcantly improve the
character in question in common wheat cultivars have failed in spite of long-term genetic and selection studies.
Possible lines of further investigation of genetic control of grain protein content and its increase in common
wheat are discussed.