ISSN 10227954, Russian Journal of Genetics, 2010, Vol. 46, No. 11, pp. 1271–1281. © Pleiades Publishing, Inc., 2010.
Original Russian Text © G.A. Gerashchenkov, N.A. Rozhnova, 2010, published in Genetika, 2010, Vol. 46, No. 11, pp. 1445–1457.
It may be said without exaggeration that the issues
of sex, sexual process, and sexual reproduction tradi
tionally occupy the central place in the theory of evo
lution [1–5]. It is known that sexual recombination
and reproduction in Protozoa occur at different time.
The classic sexual process in eukaryotes, consisting of
two alternative stages of meiosis and fertilization,
involving syngamy (fusion of gametes) and karyogamy
(fusion of nuclei) appeared much later, and its forma
tion is still under heated debate [2, 5–7]. The interest
is focused on understanding how sexual mode of
reproduction appeared in general how it is specifically
implemented in plants. How the key elements of sex
ual reproduction are controlled? What are the most
significant directions in sex evolution? Can mobile
genetic elements (MGEs) act as drivers of molecular
sex evolution and seedswithoutsex reproduction
These and many related question are not only of
great fundamental interest, but also have considerable
practical significance in connection to the possibility
of directed sex change and increase of productivity in
plants. Thus, biology of reproduction systems in plants
essentially is one of the hot spots of modern biology
. Apparently, this issue is among the most complex
problems in genetics and biology of plant reproduc
tion systems. Taking into account the complex
(epi)genetic control of sexual reproduction in plants,
it seems reasonable to consider MGEs, including ret
roelements, or retrotransposons (RTPs) and DNA
transposons (DNA TPs) as an important molecular
factors in the evolution of plant reproduction systems.
In view of the above, the aim of the present study is
considering participation of MGEs as the most proba
ble driving force in the evolution of sex in plants.
BASIC DEFINITIONS AND THEORIES
) is among the most complex and
multivalent scientific concepts in biology. In the most
general sense, this word means the set of mutually
contrasting generative (Lat.
: give birth, gener
ate) and associated traits. However, these traits differ
among species and imply not only reproductive prop
erties, but also very often the total range of sex poly
morphism. Some sexual differences are contrasting
and mutually exclusive, while others are quantitative,
exhibiting numerous individual variations. Note that
historically, understanding of the sex problem has been
formed through studying sexual reproduction of ani
mals and human [1–5] and much later was applied to
plant reproduction systems. To date, it is generally
accepted that complete, or classic, sexual process in
eukaryotes always proceeds in two stages: meiosis and
fertilization (including syngamy and karyogamy) .
As a synonym denoting sexual process and sexual
reproduction, the term amphimixis (from the Greek
, from both sides, and
, mixing) is also used.
Amphimixis is defined as the common type of sexual
reproduction involving fusion of the nuclei of a female
and male germline cells [2, 8].
The distribution of sex types over various plant
families, genera, and species is extremely varied 
(Table 1). The overwhelming majority of flowering
plants are hermaphroditic, i.e., their flowers have sta
mens and pistils—organs representing both sexes.
Mobile Genetic Elements in Plant Sex Evolution
G. A. Gerashchenkov and N. A. Rozhnova
Institute of Biochemistry and Genetics, Ufa Research Center, Russian Academy of Sciences, Ufa, 450052 Russia
Received July 29, 2009; in final form, March 9, 2010
—The most significant theories of the appearance and maintenance of sex are presented. However,
in the overwhelming majority of existing theories, the problem of sex, which is the central problem of evolu
tionary biology, is considered primarily through the prism of reproductive features of living organisms,
whereas the issue of molecular driving forces of sexual reproduction is restricted to the possible role of mobile
genetic elements (MGEs) in the appearance of sexual reproduction. The structural and functional signifi
cance of MGEs in the genomic organization of plants is illustrated. It is shown that MGEs could act as
important molecular drivers of sex evolution in plants. The involvement of MGEs in the formation of sex
chromosomes and possible participation in seedswithoutsex reproduction (apomixis) is discussed. Thus,
the hypothesis on the active MGE participation in sex evolution is in good agreement with the modern views
on pathways and directions of sex evolution in plants.
REVIEWS AND THEORETICAL ARTICLES