ISSN 1062-3604, Russian Journal of Developmental Biology, 2016, Vol. 47, No. 1, pp. 41–48. © Pleiades Publishing, Inc., 2016.
Original Russian Text © I.N. Tret’yakova, N.V. Lukina, 2016, published in Ontogenez, 2016, Vol. 47, No. 1, pp. 49–56.
Acceleration of Embryonic Development of Pinus sibirica Trees
with a One-Year Reproductive Cycle
I. N. Tret’yakova and N. V. Lukina
Sukachev Institute of Forestry, Siberian Branch, Russian Academy of Sciences,
Akademgorodok 50, bld. 28, Krasnoyarsk, 660036 Russia
Received August 28, 2014; in final form, February 13, 2015
Abstract—The study of the formation of embryonic structures in Pinus sibirica forms with a one-year repro-
ductive cycle showed that the acceleration of the embryonic process manifested itself as a reduction of the
coenocytic stage of the female gametophyte development (1.5 months instead of 1 year). The egg was not fer-
tilized because of the asynchronous maturation of male and female gametophytes. Seeds without embryos
were formed. We assumed that the acceleration of the reproductive process in Pinus sibirica was caused by a
mutation in the female generative organs.
Keywords: Pinus sibirica, cytoembryology, acceleration, one-year reproductive cycle
In Pinus species, ovules develop during two vegeta-
tive seasons. In the first year of extraovular develop-
ment, the processes of pollination and megasporogen-
esis and the formation of free-nuclear megagameto-
phyte take place. In the second vegetative season,
gametophytogenesis is completed and the processes of
fertilization and embryonic development take place
(Nekrasova, 1972; Tret’yakova, 1990).
The natural stands of Western Sayan rarely but sys-
tematically contain Siberian pine (Pinus sibirica Du
Tour) trees with a one-year reproductive cycle (Irosh-
nikov, 1974). Earlier studies have shown that these
trees are characterized by a strong development of the
crown, disturbed morphogenesis of shoots and sexual
process, and a tendency for apomixis (Minina and
Larionova, 1979; Tret’yakova, 1990; Tret’yakova et
al., 2004). Acceleration cone development is manifested
in an intense growth of seed scales, formation of seeds in
the year of pollination, and localization of female cones
on the tips of shoots on which winter shoots are usually
located (Fig. 1). The abnormal cones are characterized
by significant activation of physiological and biochemi-
cal processes—an increased content of hormonal sub-
stances and products of carbohydrate and nitrogen
metabolism in tissues (Minina and Larionova, 1979).
It is important to study the phenomenon of the
one-year cycle of development of embryological
structures in Pinus sibirica, because these forms are
unique natural models for studying reproductive pro-
cesses, speciation, and evolution in the genus Pinus
and the family Pinaceae in general.
The goals of this study were to investigate the
embryonic development of the structures of generative
organs in Pinus sibirica forms with accelerated one-
year reproductive cycle and the characteristics of seed
productivity of female cones.
MATERIALS AND METHODS
The objects of this study were seven Pinus sibirica
trees with a one-year reproductive cycle growing in the
stand of the Western Sayan (accelerant trees) and 15
grafted trees from the clonal archive of the West Sayan
Experimental Forestry (106P), whose scion was repre-
sented by cuttings of a tree with a one-year reproduc-
tive cycle (no. 106). A typical tree with a two-year
reproductive cycle (no. 277), as well as typical trees
growing in the stand of the Western Sayan that were
studied in 1974–2013, served as a control (Iroshnikov
1974; Tret’yakova, 1990, Tret’yakova et al., 2014). The
characteristics of the experimental trees are summa-
rized in Table 1.
Macrostrobili were collected in the vegetation peri-
ods of 2003–2013 at an interval of 3–4 days. Ovules
were fixed in a mixture of ethanol and acetic acid
(3 : 1 ratio). The material was further processed and
constant preparations were obtained by the conven-
tional method (Pausheva, 1978). Microtome sections
were stained with Procion dyes (Ivanov, 1983). The mac-
rostrobile seed productivity was determined according to
Minina and Tret’yakova (1983).