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Molecular Plant Breeding 2011, Vol.2, No.12, 83
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germplasm were collected from tropical rainforest.
Therefore, a fraction of this collection was probably
cultivated varieties or derived from cultivated varieties.
More collections are necessary to fill diversity gaps in
the future.
This pattern suggests that cultivars from the same or
different groups are equally important for coconut
breeders in the search for valuable traits. The main
objective in any plant genetic resources conservation
program is to maintain the highest possible level of
genetic variability covering across the gene pool of a
given species or crop, both in its natural range and in a
germplasm collection (Li et al., 2009). In order to
preserve this valuable natural germplasm resource, we
should make more efforts to protect its natural habitats
as well as to sample an appropriate number of seeds
from all these populations, which are either stored in a
gene bank (e.g. seed bank, germplasm bank) or
maintained as artificial populations in appropriate sites.
3 Materials and Methods
3.1 Plant materials
In order to represent the overall genetic diversity of
coconuts in Hainan, coconuts were collected from six
different locations. The collection sites are either
commercial or domestic plantations, locating in
various parts of Hainan province (Table 4 and Figure 2).
Table 4 Details of the accessions used in the study
Region
Plantation site (town)
Accession name
a
Number of trees analyzed
North-East
Haikou
HK-GT
5
Sanjiang
SJ-GT
4
Middle-East
Wenchang
WC-GT
5
WC-YT
6
WC-RT
4
WY
3
Changpo
CP-GT
7
Qionghai
QH-GT
4
Southern-East
Xinglong
XL-GT
4
XL-RT
3
Total
45
Note:
a
The last two characters in the name refer to the color and type of the tree (
G
green,
Y
yellow,
R
red and
T
tall); WY, a hybrid
between the local Tall and imported MYD
Figure 2 Location map of the coconuts sampled in Hainan,
China. The six different locations, where coconuts were
collected, are indicated by red stars
Tall coconuts are planted in all sites, whereas hybrids
(WY, a hybrid between the local Tall and imported
MYD) are planted in Wenchang.
3.2 DNA isolation
The total DNA was isolated from 1 g fresh leaf using
the CTAB method (Hoisington, 1992). Subsequently,
the purified total DNA was quantified by gel
electrophoresis, the DNA quality was verified by
spectrophotometry, and DNA samples were stored
at
-
20
℃
.
3.3 SSR analysis
A total of 30 pairs of highly polymorphic SSR primers
in the microsatellite kit developed by Perera et al.
(1999, 2000), Teulat et al. (2000) and Meerow et al.
(2003) were used in this study. Table 5 lists the