1022-7954/05/4103- © 2005 Pleiades Publishing, Inc.
Russian Journal of Genetics, Vol. 41, No. 3, 2005, pp. 269–274. Translated from Genetika, Vol. 41, No. 3, 2005, pp. 349–355.
Original Russian Text Copyright © 2005 by Trubacheeva, Salina, Pershina.
The construction of alloplasmic plant lines or
nucleus–cytoplasm hybrids provides a convenient tool
for studying the type of speciation during evolution and
speciﬁc features of the phenotypic expression of char-
acters resulting from variation in nucleus–cytoplasm
interactions caused by the rearrangement of nuclear
and mitochondrial genomes upon backcrossing [1–3].
Structural and functional analysis of genomes of
distant plant hybrids showed that fertility restoration
and maintenance during backcrosses and formation of
alloplasmic lines is controlled by the system of nuclear
genes that interact with genes of the mitochondrial
genome . Moreover, it was revealed that the viability
and fertility of alloplasmic lines constructed on the
basis of wheat hybrids with various species of
is determined by the presence of the
chromosome carrying the
gene, the so-
called gene of nucleus–cytoplasm compatibility .
Note that processes of mitochondrial genome rear-
rangement upon distant crossing may be manifested as
the appearance of heteroplasmy, i.e., the existence of
more than two types of extranuclear DNA molecules in
organelles and/or in cells of the particular organism .
The best studied type of the phenotypic expression of
heteroplasmy in plants is cytoplasmic male sterility
(CMS), which is often associated with the presence and
expression of novel gene variants generated by struc-
tural rearrangements in mitochondrial DNA .
Nuclear fertility-restoring genes may be involved in the
regulation of the relative number of mitochondrial
DNA (mtDNA) molecules connected with plant fertil-
ity or sterility [7, 8]. In addition, the possible reason for
the appearance of heterogeneity of the mitochondrial
genome in distant hybrids and their backcross progeny
may be a disturbance in inheritance of maternal type
typical for the majority of higher plants and the possi-
bility of mtDNA transmission from both parents .
In our recent analysis of the backcross progeny of
generations of barley–wheat hybrids
L., we revealed
the interrelation between the mitochondrial genome
organization and plant fertility expression . Thus,
heteroplasmy, i.e., the presence of both maternal (bar-
ley) and paternal (wheat) DNA copies, was shown to be
characteristic of sterile or partially fertile backcross
generations and alloplasmic wheat lines obtained on
their basis, whereas only paternal DNA fragments were
detected in alloplasmic lines with restored fertility.
Meanwhile, no fragments of the barley genome were
found in the nuclear genome of alloplasmic lines with
partial or complete fertility .
Earlier, on the basis of barley–wheat hybrids
L., a great variety of self-
fertile recombinant alloplasmic lines were obtained
among self-pollinated backcrossed progeny of hybrids
and their amphiploids [12, 13]. We established that the
gradual replacement of barley nuclear genome with
wheat genome upon backcrossing causes the introgres-
sion of barley genome fragments into the newly recon-
structed wheat genome . These lines are interesting
models for studying the speciﬁc structure of the mito-
chondrial genome and the probability of the appearance
of mitochondrial DNA heteroplasmy, depending on the
stability of self-fertility manifestation in plants and on
Study of Mitochondrial Genomes
of Allopllasmic Recombinant Wheat Lines
Constructed on the Basis of Barley–Wheat Hybrids
N. V. Trubacheeva, E. A. Salina, and L. A. Pershina
Institute of Cytology and Genetics, Russian Academy of Sciences, Novosibirsk, 630090 Russia;
fax: (3832) 33-12-78; e-mail: firstname.lastname@example.org
Received August 17, 2004
—Using RFLP analysis with three probes homologous to speciﬁc regions of mitochondrial DNA
genes and PCR analysis of the mitochondrial recombining-repeat-sequence 18S/5S region of cereals, ﬁve allo-
plasmic wheat lines of different origin and fertility expression were studied. These lines are self-pollinated
progeny of BC
generations of barley–wheat hybrids
= 42). It was found that recombinant alloplasmic lines characterized by partial fertility contain
either maternal (barley) DNA fragments or maternal and paternal (wheat) DNA fragments simultaneously (het-
eroplasmy). In lines with stable expression of self-fertility, fragments of only paternal mitochondrial DNA were
detected. It is assumed that in alloplasmic lines, there is the interrelation between the presence of deﬁnite frag-
ments of the mitochondrial genome belonging to either parental type and fertility expression.