INTRODUCTION
Caryopteris incana (Thunb.) Miq. is a perennial plant or shrub
natural to China, Taiwan, Korean Peninsula, and Japan.
Plant height may exceed 1 m from 30 cm, stand upright, and branch.
Opposite leaves egg-sharped have strongly aromatic with coarsely
serrate, and their surface is a grey-green color [1].
Cymes extend from the axillae above the stem with blue-violet, fragrant
flowers.
The inflorescence has a ring-like flower cluster on the stem and blooms
from the lower part to the upper part.
It is a short-day plant that blooms from September to October, and the
upper leaves die after 1 ~ 2 months of blooming.
In early winter, a few leaflets remain in a rosette and overwinter.
It is used for horticultural purposes, as well as for flower arrangement
and garden planting.
In particular, many of cultivar group of Caryopteris ×clandonensis A. Simmonds by mating C. incana (seed parent)
with C . mongholica Bunge.(pollen parent) is used as a
garden plant or cut flower mainly in Europe and the United States
because it is a hardy horticultural plant [2].
However, cultivars or C. incana in circulation have only 3 color
of flowers is blue-violet, white (C . incana f.candida C.K. Schneid.), pink (C . incana f.rosea Sugim.), few cultivars distinguished in the form except the
flower color are produced.
Therefore, it is necessary to obtain phenotypic information in wild
types as a breeding material for diversifying horticultural cultivars ofC. incana, C.×clandonensis .
Outside of these horticultural uses, C. incana contains several
phenylpropanoid glycosides, including the proprietary incanoside (Gao
and Han, 1997; Gao et al ., 1999, 2000; Li and Wang, 2004; Zhaoet al ., 2009), which is used in China as folk medicine with
medicinal properties against pertussis, menstrual irregularities,
eczema, and rheumatic pain [1,3].
In addition, GC/MS analysis of volatile compounds showed that fumigants
and essential oils from C. incana exerts potent insecticidal
effects against the weevil, Euscepes postfasciatus, a stored grain pest
in Poaceae [4].
In addition to the horticultural ornamental value, C. incana has
the value as a functional plant.
C. incana is considered to be one of the continental plants that
remain on the islands of western Kyushu and western mainland Japan (Ito,
1997), and its natural environment in Japan is limited to western Kyushu
[5,6].
C. incana , which grows mainly in exposed rocky areas, shows
lithophytic features, such as in soil and in crevices where organic
matter accumulates. And is sometimes observed in the same assemblage asSelaginella tamariscina (P. Beauv.) Spr. [6].
Based on these natural environments, it is considered that each natural
population of C. incana is distributed locally (not
continuously), and that it exists in multiple local populations in the
same region.
In addition, the number of indigenous populations has been declining due
to destruction of natural environments, mainly due to land reclamation,
road maintenance, trampling, etc., and was listed in the Red Data Book
in 2000 as Endangered Class II (VU) [7].
An investigation of the habitat of C. incana in Japan was
reported by Itow and Kawasato (1988) in 1988 [6].
Since the distribution of C. incana had not been investigated
since this survey, we conducted a habitat survey in western Kyushu,
Japan [8,9].
We identified 72 populations on Tsushima, Nagasaki Prefecture, 16
populations on the mainland of Nagasaki, 16 populations on the Goto
Islands, and 109 populations on Koshikijima Islands, Kagoshima
Prefecture (Fig. 1).
Among these areas, we confirmed that the indigenous population tended to
decrease in the mainland of Nagasaki.
In addition, DNA was extracted from the seedling of the seeds collected
from each natural population, and the chloroplast DNA was sequenced.
As a result, interpopulation variation was identified in 6 regions of
chloroplast DNA, and a total of 22 haplotypes were identified, including
6 types in Tsushima, 6 types in the Nagasaki mainland, 9 types in the
Goto Islands, and 3 types in the Koshikijima Islands.
Phylogenetic analysis revealed multiple sequence variation between these
haplotypes and populations distributed in the Tsushima, Nagasaki
mainland, and the Goto Islands, the Koshikijima Islands, and parts of
Nagasaki mainland, and they were classified into two groups, suggesting
early disjunction between these regions.
We also identified common haplotypes in natural populations in the
northwestern part of Nagasaki mainland and the Koshikijima Islands.
Base on these results, we clarified the genetic structure and genetic
diversity among wild populations of giant reed in western Kyushu based
on chloroplast DNA.
On the other hand, the phenotypic diversity of the C. incana has
not been studied.
As C. incana is characterized as a chasmophyte plant, it has a
localized assemblage of individuals that can be recognized as a
population and grows in a spatially isolated state.
Therefore, there is a possibility that the phenotype variation adapted
to the natural environment occurs in each population.
The objective of this study was to investigate phenotypic variation in
each natural population by growth survey and to evaluate its association
with geographical structure.
These results suggest that the phenotypic diversity of the indigenous
population in western Kyushu and comparison with the genetic structure
in chloroplast DNA may clarify the relationship between phenotypic
variation and genetic variation.
Information on these phenotypes may contribute to the utilization of
plant resources such as breeding materials and the planning of
conservation programs as endangered species.