1022-7954/02/3812- $27.00 © 2002
Russian Journal of Genetics, Vol. 38, No. 12, 2002, pp. 1391–1396. Translated from Genetika, Vol. 38, No. 12, 2002, pp. 1641–1647.
Original Russian Text Copyright © 2002 by Larionova.
L. is one of the major
forest conifer species in Eurasia . Because of its high
plasticity, it occupies a vast area from 37
from the Atlantic coast to 120
E . Within this area,
Scotch pine is variable over a wide range of morpholog-
ical and ecophysiological traits and forestry properties.
It includes over 20 geographical races and about
100 varieties .
Numerous studies were dedicated to Scotch pine.
The most complete review of its variability and
intraspeciﬁc systematics was presented by Pravdin .
However, it should be noted that the studies concerned
mainly morphological traits whose complex inherit-
ance hampers investigation of genetic diversity of pine
populations. Knowledge of the level and nature of
genetic diversity in natural populations is important not
only for investigation of evolution and intraspeciﬁc dif-
ferentiation but also for development and implementa-
tion of combined programs for preservation, reproduc-
tion, and improvement of forest resources.
The genetic variability in conifers is typically inves-
tigated with the use of electrophoretic assay of mono-
genically inherited isozymes. Experiments with
isozymes as biochemical gene markers provided data
on the genetic structure, allelism, and genetic variabil-
ity parameters of different Scotch pine populations
[4–24]. However, these studies did not cover the whole
range of Scotch pine. Virtually nothing is known about
the genetic diversity of the species in the southeastern
part of this area. Scotch pine populations occurring in
isolated steppe forests of Southern Siberia are of great
interest for genetic studies. They are enriched in forms
rare in other areas and individuals plants with various
defects in development of vegetative and reproductive
organs [25, 26].
This paper presents the results of electrophoretic
isozyme analysis of the genetic variability of Scotch
pine in Chita oblast. The objectives of the study were:
understanding the genetic control of the diversity
among nine polymorphic enzymes of Scotch pine and
determining genetic variability indices in the popula-
tion at the structural genes found.
MATERIALS AND METHODS
The study was performed in a natural Scotch pine
population occurring in the southeast of Chita oblast,
Transbaikalia. In this region, Scotch pine has long been
spatially and temporally isolated. It experiences strin-
gent natural selection under the severe conditions exist-
ing in the forests. Scotch pine from this area differs
from that from other areas in having larger cones, larger
seeds (1000 seed weight), higher seed quality, higher
growth rate and better preservation of seedling .
Experiments were performed with seeds harvested
from individual trees over an experimental plot founded
by Dvoretskii in the Tsasuchei Forest . Seeds were
germinated until the appearance of a root. Then the
hard covers were discarded, and the endosperms and
embryos were homogenized separately in one or two
drops of extraction buffer (0.1 M Tris-HCl, pH 7.5). The
extraction lasted for an hour.
Extracts were analyzed by vertical and horizontal
electrophoresis in 13% starch gel. Three buffer systems
were used for electrophoresis: (A) Tris-EDTA borate
pH 8.65 ; (B) Tris-citrate, pH 6.2 ; and (C) Tris-
citrate, pH 8.5/LiOH-borate, pH 8.1 . The compo-
sitions of the gel and electrode buffers and electro-
phoresis conditions were as recommended in the litera-
ture. Histochemical detection of the enzymes was per-
formed according to conventional protocols [31, 32]
with some modiﬁcations. The enzymes analyzed, their
designations, classiﬁcation codes, buffer systems, and
Genetic Variability in Scotch Pine
in the Southeastern Part of Its Range
A. Ya. Larionova
Sukachev Institute of Forestry, Russian Academy of Sciences, Krasnoyarsk, 660036 Russia;
e-mail: firstname.lastname@example.org; fax: (3912) 43-36-86
Received December 29, 2001
—The main parameters of genetic variability have been determined in an isolated natural Scotch pine
population from Chita oblast (Tsasuchei Forest) by analysis of 19 genes coding for nine enzymes: GDH, IDH,
LAP, PGM, AAT, ADH, MDH, 6-PGD, and DIA. Polymorphic genes constituted 63.2% of all structural genes
studied in the population at the 99% polymorphism criterion. The mean number of alleles per locus was 1.63.
The observed and expected heterozygosities were 0.237 and 0.251, respectively. These estimates are close to
the corresponding mean values for Scotch pine according to the data on 18 or more structural genes.