ISSN 1022-7954, Russian Journal of Genetics, 2006, Vol. 42, No. 11, pp. 1324–1328. © Pleiades Publishing, Inc., 2006.
Original Russian Text © G.I. Naumov, E.S. Naumova, V.I. Kondratieva, 2006, published in Genetika, 2006, Vol. 42, No. 11, pp. 1571–1576.
Eukaryotic microorganisms possessing a sexual
process or its analog, a parasexual process, are avail-
able for genetic breeding programs based on hybridiza-
tion and recombination. Century-old experience of
experimental breeding of higher eukaryotes has pro-
vided the theory and methods of generating highly pro-
ductive animal breeds and plant varieties. Unfortu-
nately, microbiologists working in the ﬁeld of breeding
underuse the achievements of their colleagues, albeit
the genetics of many eukaryotic organisms is studied in
many details by means of classic and molecular meth-
ods. The main reason for the gap between breeding and
genetics of eukaryotic microorganisms, to our opinion,
lies in the fact that microbiologists have still not
accepted the biological species concept, as well as the
synthetic theory of evolution, elaborated for higher
eukaryotes. Until recently, many microbiologists even
did not admit the existence of biological species of
eukaryotic microorganisms as isolated genetic popula-
Recent reviews on breeding programs of baker’s,
brewery, wine, and distiller’s yeasts have mostly focused
on the use of induced and physiological mutants [1–5].
Among earlier breeding reports, the publications of
Inge-Vechtomov  and Kosikov  are worthy of
In the present review, we summarize the data on the
use of hybridization techniques in breeding programs
and suggest a genetic
program to be introduced in breeding studies.
Breeding studies and genetic investigations require
basic material in the form of highly fertile inbred lines.
Generation of such lines is the top-priority. Freshly iso-
lated natural, museum, and especially industrial strains
often form nonviable meiosis prod-
ucts, viz. ascospores. This phenomenon can be caused
by many factors, including odd polyploidy, aneuploidy,
interspeciﬁc hybridization, heterozygous lethal muta-
tions, inversions, deletions, and translocations. Usually,
single-spore cloning in the ﬁrst or, rarely, second gen-
eration, is sufﬁcient in the case of homothallic strains
. At the same time, works with heterothallic yeasts
require inbreeding up to tenth generation . Single-
spore cloning in fertile strains is usually performed
with the help of a micromanipulator, while, in low-fer-
tile yeasts, a spore sample is prepared after elimination
of vegetative cells by means of ether treatment .
Involvement of inbred lines with the known genotype
into breeding programs provides for highly reproduc-
ible mating results. In our laboratory, inbred lines were
constructed using a great number of industrial and nat-
ural strains [8, 11].
In yeast genetics, methods of mass mating of hap-
loid cells with subsequent zygote screening with the
use of a micromanipulator or selective media are widely
used . Micromanipulation by spore-per-spore or
spore-per-haploid-cell methods is also possible . All
these approaches can be applied for yeast breeding. Con-
cerning strain marking, it is advisable to use either the
spontaneous mutations on the selective media
with antimetabolites or the induced
ing to the development of red colonies .
In the case of hybridization of strains of independent
origins, the effect of interstrain heterosis can be
expected. The cumulative polygenic control of quanti-
The Use of Hybridization in Breeding
of Eukaryotic Microorganisms
G. I. Naumov, E. S. Naumova, and V. I. Kondratieva
State Research Institute of Genetics and Selection of Industrial Microorganisms, Moscow, 117545 Russia;
Received April 10, 2006
—The article deals with the genetic bases of breeding of eukaryotic microorganisms. Using the data
yeasts, application of different genetic approaches and methods to breeding is discussed,
including interstrain, interlinear, and distant interspeciﬁc hybridization, as well as heterosis, polyploidy, cyto-
duction, and meiotic recombination.