Botanical Studies (2008) 49: 147-153.
*
Corresponding author: E-mail: xjge@yahoo.com; Tel:
+86-20-3725 2551; Fax: +86-20-3725 2831.
POPULATION GENETICS
Population genetic structure of Camellia nitidissima
(Theaceae) and conservation implications
Xiao WEI
1, 2
, Hong-Lin CAO
1
, Yun-Sheng JIANG
2
, Wan-Hui YE
1
, Xue-Jun GE
1,*
, and Feng LI
2
1
South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, P. R. China
2
Guangxi Institute of Botany, Guangxi Zhuangzu Autonomous Region and Chinese Academy of Sciences, Guilin 541006,
P.R. China
(Received January 11, 2007; Accepted October 19, 2007)
ABSTrACT.
Camellia nitidissima Chi (Theaceae), with its golden-yellow flowers, is a famous ornamental
species. Due to deforestation and collection of seedlings, its natural populations have receded greatly in recent
decades. Genetic diversity and genetic differentiation of the twelve extant natural populations and one ex situ
conserved population of C. nitidissima in China were analyzed using inter-simple sequence repeats (ISSR)
markers. We found a low level of genetic diversity at both the species (P = 63.22%, Nei”¦s genetic diversity
H
T
= 0.1561 and Shannon diversity Hsp = 0.2490) and population levels (P = 18.77%, H
E
= 0.0831 and
Hpop = 0.1188) and a relatively high degree of differentiation among populations (AMOVA analysis: 41.85%;
Hickory £c
B
: 0.4056) in naturally occurring populations. In contrast, the ex situ population contained higher
genetic variability compared to each natural population. No significant correlation was found between genetic
diversity and population size. Based on the results, we suggest that all the wild C. nitidissima populations
should be protected in situ. For the ex situ conservation of the species in Guilin Botanical Garden, samples
from Long”¦an County should be added to the existing collections.
Keywords: Camellia nitidissima; China; Endangered species; Ex situ conservation; ISSR fingerprinting; Small
population size.
INTrODUCTION
The section nitidissima Chang of the genus Camellia
(Theaceae) comprises 18 rare and endangered species
occurring in a narrow range 20¢X32”¦-23¢X53”¦ N, 104¢X-108¢X
56”¦ E, and at the altitudes of 50-650 m, in Southwest China
and North Vietnam (Zhang, 1996). The golden-yellow
petals of the flowers have earned them the title "the queen
of the Camellia family" (Liang, 1993). They represent
valuable germplasm resources for cultivar breeding,
especially for producing yellow flowers. With the big size,
golden color, and the transparent waxy appearance of its
flowers, Camellia nitidissima Chi is the most interesting
species of the section. Although first discovered in
Fangcheng County in 1933 and reported to the public in
1948, C. nitidissima received no attention from the public
or horticulturists until the early 1960”¦s when it was found
again in Yongning County (Deng et al., 2000). Camellia
nitidissima is a diploid shrub (2n = 30, Huang and Zhou,
1982), with a restricted distribution in the southwestern
Guangxi Zhuang Autonomous Region in China and in the
neighboring regions of North Vietnam. It grows under
shady and moist evergreen broad-leaf forests dominated
by Canarium album, Dendrobenthamia hongkonensis,
and Canstanopsis cuspidata. Its big and colorful flowers
(diameter: 1.2-2.3 cm) blossom from November to March
and set fruits in the spring.
Due to deforestation of the regions where C. nitidissima
grows and the over collection of its seedlings, its natural
population has declined dramatically in recent decades.
It is now classified as one of the most endangered
plant species in China (Fu, 1992). In order to protect
this valuable genetic resource, one natural reserve was
established in Fangcheng in 1986. In addition to the
in situ habitat preservation for rare and endangered
plant species, ex situ conservation in botanical gardens
plays an important role in conserving these plants. In
the 1980s, Guilin Botanical Garden (GL) started an ex
situ conservation program for this species and planted
more than 1300 seeds and 100 seedlings collected from
Yongning, Fangcheng, Dongxing, and Fusui Counties.
Today, about 800 individuals are settled in the garden, and
most of them blossom and set fruits.
Although the morphology (Ye and Xu, 1992), ecology
(Su, 1994; Huang, 2001), and condition for cultivation
(Zhang and Huang, 1984) have been studied, the popula-
tion genetic structure of this endangered species has never
been examined extensively across the species range (Bin et
al., 2005; Tang et al., 2006). Understanding the levels and