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Plant Gene and Trait 2012, Vol.3, No.8, 43
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understanding their future maintenance and developing
improvements in conservation programs (Mahar et al.,
2011). Meanwhile, there are many available molecular
methods to analyze the genetic variability in plant
species, but no single method is universally applicable
(Mahar et al., 2011). Many researchers use molecular
methods to estimate genetic diversity (Su et al., 2009;
Hafezi Shahroodian et al., 2011; Buiteveld et al., 2007;
El-Kassaby et al., 2003; Wang et al., 2004).
In the present study, we used Simple Sequence Repeat
(SSR or microsatellite) markers to estimate the genetic
variability in
C. sempervirence
individuals. SSRs are
tandem repeated units of nucleotides that are abundant
in prokaryotic and eukaryotic genomes and are
ubiquitously distributed in both genome’s protein-coding
and non- coding regions (Field and Wills, 1996; Toth
et al., 2000). The hyper variability and co-dominance
of SSRs, their dispersion throughout genomes and
suitability for automation are the principal reasons for
their wide utility (Powell, 1996; Jarne, 1996; Gupta,
1996). These markers have been used to characterize
genetic diversity in plants (Zhang et al., 2007; Hafezi
Shahroodian et al., 2011; Chen et al., 2009; Angielina
et al., 2011).
Sixty three individuals of
Cupressus sempervirens
from all regions of Iran were examined to quantify
genetic diversity and genetic structure by SSR
markers. These trees were selected for the research
because of their adaptive potentials. The spatial
variation in tree genetic diversity, in turn, determines
the adaptability of tree populations to environmental
change and is thus essential for the long-term
sustainability of forest ecosystems (Giannini et al.,
1991; Rehfeldt et al., 2002; Bilgen and Kaya, 2007;
Savolainen et al., 2007). The main objective of the
present study was to evaluate genetic variability and
degree of genetic divergence within long-lived indivi-
duals of
Cupressus sempervirence
.
1 Results
The total number of alleles per locus is listed in Table
1. A total of 113 alleles were detected, the mean
number of alleles per locus was 14.12. The number of
observed alleles in all the individuals per locus varied
from 8 for Cyp84 and Cyp258 to 25 for Cyp250. The
most of eight loci assayed possessed a high level
of polymorphism, with the number of the effective
alleles per locus ranging from 1.23 at Cyp250 to 1.55
at Cyp293. The PIC value was also estimated, as
shown in Table 1 with the highest value (0.32) for
Cyp52 and the lowest values (0.16) for Cyp250
(Figure 1). Nei’s gene diversity (H
E
) ranged from 0.16
to 0.32 and the average expected heterozygosity (H
E
)
and the mean Shannon indices (H
O
) was 0.26 and 0.41,
respectively.
In order to distinguish the best clustering and similarity
coefficient calculation methods, the cophenetic co-
rrelation, a measure of the correlation between the
similarity represented on the dendrograms and the
actual degree of similarity, was calculated for each
method combination. Among different methods, the
Table 1 Observed and effective number of alleles, Nei’s gene Diversity, Shannon’s index and polymorphic information content (PIC)
for eight microsatellite loci analyzed in 63 individuals of
Cupressus sempervirence
Primer
Observed number of alleles
Effective number of alleles
Nei’s gene diversity
Shannon’s index
PIC
Cyp52
17
1.52
0.32
0.48
0.32
Cyp84
8
1.51
0.29
0.44
0.29
Cyp101 20
1.30
0.21
0.36
0.21
Cyp139 18
1.41
0.27
0.43
0.27
Cyp250 25
1.23
0.16
0.29
0.16
Cyp257
7
1.39
0.24
0.39
0.24
Cyp258
8
1.47
0.27
0.42
0.27
Cyp293 10
1.55
0.31
0.46
0.31
Mean
1.42
0.26
0.41
0.26
St.Dev
0.31
0.15
0.20
Total
113