Table Of Content植物研究雑誌
J. Jpn. Bot.
81: 107-112 (2006)
Karyomorphogical Analysis of Diploid Races of
Aucubajaponica Thunb. (Cornaceae)
Machiko TSUSAKA，H iroshi IKEDA and Tak吋iHOSHINO
Department of Mathematical and Environmental System Science，G raduate School of Informatics，
Okayama University of Science，1 - ，1Ridai-cho，O kayama 700-0005 JAPAN
E-mail: [email protected]
(Received on October 6，2 005)
A karyomorphological analysis of diploid races of Aucubαjaponica Thunb.，w ith
special reference to their sexualities，w as carried ou .tAfter examining 59 individuals
from 16 localities in the Chugoku and Shikoku Districts，w estern Japan，al l individuals
proved to be diploid with 2n =1 6，a nd the smallest pair of chromosomes had as atellite
on each short arm. Among the 59 individuals，2 4 individuals “(heterotype") possessed a
heterogeneous pair of chromosomes composed of median and submedian chromosomes
in the fourth longest pair. The remaining 35 individuals “(homotype") possessed homoge-
neous pair with median chromosomes in the fourth longest pair. Such cytological varia
副
tion did not show ag eographical tendency，b ut all the “heterotypes" were observed in
male individuals，a nd “homotypes" were in female individuals. Therefore we have con-
cluded that the karyomorphological variations in diploid races of A. japonica depend on
their sexualities.
Key words: Aucuba japonica，di ploid race，k aryomorphology，s ex chromosome.
Aucuba japonica Thunb. (Comaceae) is Chromosome numbers have been reported to
distributed throughout Japan，f rom southern be 2n = 32 (tetraploid) for v訂s.japonicαand
Hokkaido to Okinawa，a nd in Korea and borearis and to be 2n = 16 (diploid) for var.
Taiwan. It is an evergreen dioecious shrub ovoidω(Meurman 1929，F unabiki 1958，
mainly growing in temperate forests. Aucuba Kurosawa 1971). Karyotype analyses have
japonica is usually classified into three va- been made mainly for tetraploid races
rieties，v ars. japonica，b orealis Miyabe & (Meurman 1929， Sinoto 1929， Viinikka
Kudo，a nd ovoidea Koidz. Variety japonica 1970)，a nd such studies of diploid races have
is distributed from the Tohoku District to the not been extensively carried out. Kurosawa
Chugoku and Shikoku Districts mainly on (1971) compared the karyotypes of diploid
the Pacific Ocean side. Variety boreαlis is and te佐aploidraces.
distributed from southem Hokkaido to the Sex chromosomes have been reported in
Kinki District through the Tohoku and several dioecious plants，m ainly in herbs
Hokuriku Districts，m ainly on the Japan Sea such as Rumex (Kihara and Ono 1923，L ove
side. Variety ovoidea is distributed from 1943)，M elandrium (Blackbum 1923，W inge
eastern part of the Chugoku and Shikoku 1923)， Humulus (Winge 1923)， and
Districts to the Kyushu District and also in Cannabis (Sinoto 1929)，a nd relatively few
the Amami and Okinawa Islands (Hara 1966， in woody plants such as ，5αlix (B lackburn
1989， Noshiro 1999， Ohi et al. 2003). and Harrison 1924)，a nd Palmae (Sinoto
-107-
108 植物研究雑誌第81巻第2号 平成18年4月
1929). On the genus Aucuba，n o sex chromo- Science (OKAY ).
some has been reported. Sugiura (1927)，
Meurman (1929) and Sinoto (1929) observed Results and Discussion
chromosomes of teaploidraces of A. japon- After examining chromosomes of Aucubα
位
ica and noted that there was no sex chromo- japonica collected from 16 localities in the
some among 32 somatic chromosomes. Chugoku and Shikoku Districts，al l individu-
Kihara and Yamamoto (1935) examined A. als proved to be diploid with 2n = 16 (Table
chinensis (2n =1 6)，a nd Kurosawa (1971) 1). Figures 1a nd 2s how somatic chromo-
examined A. chinensis and A. himalaica somes and karyotypes of diploid races of A.
(2n = 16) cytologically，b ut they did not japonica，re spectively. The length of somatic
mention sex chromosomes. chromosomes efrom 3.6 to 7.1μm，a nd
紅
This paper aims to provide an accurate kaηomo叩hologically，the complement is
report of karyomorphology of diploid races mono-modal. Eight chromosome pairs were
of A. japonica，w ith special reference to sex recognized by configuration of chromo-
or sex-dependent chromosomes. somes: three large-sized pairs with
subterminal to submedian chromosomes，o ne
Materials and Methods medium-sized pair with median chromo-
Fifty-nine individuals were collected from somes， and four smallsizedpairs with
司
16 localities in the Chugoku and Shikoku subterminal to median chromosomes. The
Districts，w estern Japan (Table 1). Young smallest pair had comparatively large satel-
branches were propagated hydroponically lites on the short 'ms.Kurosawa (1971) ob-
紅
and wer also arranged as herbarium speci- served several diploid individuals of A.
mens. Root tips were preeatedwith 0.002 japonica collected from the Ky ushu District
佐
M 8-hydroxyquinoline solution for an hour and the Okinawa Island. Although the pre
皿
at 200Ca nd stored 15 hours at 40C，th en they sent study has confirmed that the smallest
were fixed with a3 : 1m ixture of 99.5 % pair has satellites，it is not clear whether the
ethanol and glacial acetic acid at -200Cm ore large-sized pairs have satellites or not. Other
than one hour. The root tips were hydrated methods，su ch as FISH，C- banding，or silver-
and were soaked in al N HCl solution for 10 staining methods，s hould be applied to con-
minutes at 60oC，a nd were transferred to firm the number and position of satellites.
Schiff' sr eagent at room temperature for an During the analysis of k紅yomorphology，
hour. Then the materials were macerated we found that 24 individuals out of the 59 IIト
with as olution of am ixture of 2% cellulase dividuals possessed ah eterogeneous karyo-
and 2% pectinase for 30 minutes at 370C， type with one median and one submedian
and washed in distilled water. The chromosomes in the fourth longest pair
meristematic tissues were placed on slide “(heterotype"). The remaining 35 individuals
glasses and were squashed with an aceto- possessed median chromosomes in the pair
glycerin (45 % acetic acid with a small “(homotype") (Figs. 1，2 ). All the “hetero
目
amount of glycerin) and observed by types" were found to be male individuals，
microscope. Mitotic metaphase chromo- and “homotypes" to be female individuals
somes were microphotographed and were (Table 1). As “heterotype" individuals were
karyotypically analyzed. Chromosomes were distributed throughout the research area and
c1assified into several types，f ollowing the found in four populations with “homotype"
nomenclature of Levan et al. (1964). individuals (Table 1)，w e have concluded
Vo ucher specimens are deposited in the that the kyomorphologicalvariation in
紅
Herbarium of Okayama University of diploid races of A. japonica is not geographi-
Apri12006 Journal of Japanese Botany Vol. 81 No. 2 109
Table 1. Collection data，c hromosome numbers，a nd karyotypes of diploid races of Aucuba japonica
Number of Chromosome
Locality (collector，v oucher specimen number，al titude) Sex individuals number (2n) Karyotype
examined
Okayama Prefecture
Ukankei，S himokamo，K ibichuo-cho (M. Tsusaka & a .l ♂ 16 hetero*
TS04100602，1 50 m)
Ukankei，S himokamo，K ibichuo-cho (M. Tsusaka & a .l ♀ 2 16 homo**
TS04100603，0 4100610，1 50m)
Ukankei， Shimokamo， Kibichuo-cho (M. Tsusaka ♀ 4 16 homo
0505032XF，1 50 m)
Ukankei， Shimokamo， Kibichuo-cho (M. Tsusaka ♂ 2 16 hetero
0505032XM，1 50 m)
Iwayakei， Kawakami-cho， Takahashi-shi (M. Tsusaka 。 16 homo
T
03052401，1 50 m)
Nunose，B itchu-cho，T akahashi-shi (M. Tsusaka & a .l ♂ 2 16 hetero
050220A，1 50 m)
Shimane Prefecture
Fukamachi pond，N ishikawazu-cho，M atsue-shi (S.-J. Lin ♂ 16 hetero
04041901，3 0 m)
Naku，O kinoshima-cho (M. Tsusaka 03102502，3 20 m) o 16 homo
T
Yamaguchi Prefecture
Kamitama，T amagawa-cho (M.Tsusaka 03041303，1 0 m) ♀ 16 homo
Tokushima Prefecture
Minamikumaso，K amiyama-cho (M. Tsusaka 05072201，9 0 o 16 homo
T
m)
Minamikumaso，K amiyama-cho (M. Tsusaka 05072201，9 0 ♂ 16 hetero
m)
Kochi Prefecture
HHiiggaasshhii--iisshhiihhaarraa，，TT oossaa--cchhoo ((MM.. TTssuussaakkaa 005500331144AA22，，55 6600 mm)) 。↑切。 11 咽-EA--E且uroぷ hheotmeroo
SSShaaikkraaaggiaawwwaaado，，，TT Koo ssaaagyyaaammmiaa，ddKaa o--ccchhhi-oos h((iMM ..( MTT.ss uuTsssaaukksaaa k00a55 0005330113331AA4ll，，，288 8 225 mmm))) 60TO引升 19H 4EEi--EAe--且zO/O/O hhheeottmeerrooo
NNIKiauabsggouaa，sssYe aau，swwIuaa nh，，oaII-r nncaooh---occc hhh(oooM .((( MMMT...s uTTTssssauuuksssaaaa kkkTaaaS 00003455010060331011364400AA14ll，，，，4466 90 110 00m m)mm) )) OTOT判。。十 8412 且唱4EaA4a-A4EE'B-A/orOO/O〆 hhhheoootmmemroooo
Shimokurechi，K ubokawa-cho (M. Tsusaka 04101303，3 50 OT 1 唱・・A/O homo
m)
Ooino，K ubokawa-cho (M. Tsusaka 04101302，320 m) ♀ 16 homo
Ehime Prefecture
Ohkuki，U chiko-cho (M. Tsusaka 04101202，1 60 m) o 2 16 homo
T
*hetero: the fourth-1ongest pair with heterogeneous chromosomes.
homo:the fourth-longest pair with homogeneous chromosomes.
料
cal nor populational variation，b ut coes- therefore supposed that the fourth chromo-
町
ponds to the sexuality. Karyomo中hological some pairs are sex chromosomes.
variation coespondingto sexuality in A. The reports of sex chromosomes in
町
japonica is reported for the first time. It is dioecious plants have been mainly for herbs
110 植物研究雑誌第81巻第2号 平成18年4月
Fig. 1. Sornatic chrornosornes of diploid races of Aucubαjaponica. A-C: Fernale，D -F: Male. A: Ukankei‘
Okayarna Pref. B: Nagasawa，Ko chi Pref. C: Iibo，Ko chi Pref. D: Nishikawazu-cho，Sh irnane Pref. E:
Ukankei，O kayarna Pref. F: Takahashi-shi，O kayarna Pref. Arrows indicate the fourth-longest pair with
hornogeneous chrornosornes (A-C) and heterogeneous chrornosornes (D-F). Arrowheads indicate satel-
lite chrornosornes. Bar = 10 flrn.
(Blackbum and Harrison 1924，M eurman dioecious evergreen shrubs like A. japonica.
1925，L indsay 1930，L ove 1943， Sinoto The heteromorphic chromosomes observed
1929，W inge 1923)，a nd relatively few for in diploid races of A. japonica are supposed
woody plants (Blackbum and Harrison 1924， to be sex chromosomes and this is the first
Meurman 1925，Li ndsay 1930，Si noto 1929). report of sex chromosomes for evergreen
There is no report on sex chromosomes for shrub.
Apri12006 Journal of Japanese Botany Vol. 81 No. 2 111
、
11111 i ，.. i
jl J I I も
A
Fig.2. Kaηotypes of diploid races of Aucuba japonica. A: Nagasawa，K ochi Pref. (♀). B:
Nishikawazu，S himane Pref. (♂). Arrows indicate the fourth-longest pair with homogeneous
chromosomes (A) and heterogeneous chromosomes (B). Arrowheads indicate satellite chromo-
somes. Bar = 10μm.
We thank Mr. Shungo Kariyama， Kurosawa S. 1971. Cytotaxonomical studies on the
Kurashiki Museum of Natural History，M r. genus Aucuba. J. Jpn. Bot. 46: 231-238.
Makoto Ogawa， Tokushima Prefectural Levan A.，F redga K. and Sandberg A. A. 1964.
Nomenclature for centromeric position on chromo-
Museum，a nd Dr. Tetsuo Ohi，B otanical
somes. Hereditas 52: 201-220.
Garden of the University of Tokyo，fo r their
Love A. 1943. Cytogenetic studies on Rumex subgenus
valuable information on distribution of Acetosella. Hereditas 30: 1-136.
Aucubajaponica. Wea lso appreciate Dr. Su- Lindsay R. H. 1930. The chromosomes of some
Jang Lin，S himane University，fo r sending a dioecious angiosperms. Amer. J. Bot. 17: 152-
174.
material. This study is partly supported by
Meurman O. 1925. The chromosome behaviour of
the Yakumo Foundation for Environmental
some dioecious plants and their relatives with spe-
Science in 2005 (to M. T.). cial reference to the sex chromosomes. Soc. Sci.
Fennica，C ommentat Biol. 2: 1-105.
1929. Chromosome numbers in the family
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津坂真智子，池田 博，星野卓二:アオキ(ミズ
キ科)の2倍体における核形態学的解析
ミズキ科アオキ (Aucubajaponica Thunb.)の二 ホモ型と，中部動原体染色体と次中部動原体染色
倍体 (2n= 16)について，雌雄性を考慮して核型 体を一本ずつもつヘテロ型の組み合わせをもっ個
分析を行った.中国・四国地方産のアオキ16地点 体が見出された.この変異は地理的なものではな
59個体について解析を行ったところ，すべての個 く，ホモ型の組み合わせをもっ個体はすべて雌で
体で最小の染色体対に付随体がみられ，これまで あり，ヘテロ型の組み合わせをもっ個体はすべて
の報告と→致した.しかし これまで指摘されて 雄であることが明らかになった. したがって，ア
いた最大の染色体対と三番目に長い染色体対にあ オキの二倍体は，性によって異なる核型を示し，
るとされる二次狭窄については，今回の研究では 性染色体をもっていると考えられる.
明瞭に識別することはできなかった.また，四番 (岡山理科大学総合情報研究科
目に長い染色体対に中部動原体染色体を 2本もつ 数理・環境システム専攻)
