全 文 ：类叶升麻具有毛茛科中最对称和最原始的核型吗 ?
杨 亲 二
(中国科学院植物研究所系统与进化植物学开放研究实验室　北京 100093)
DOES ACTAEA ASIATICA HAVE THE MOST SYMME-
TRIC AND PRIMITIVE KARYOTYPE IN
THE RANUNCULACEAE ?
YANG Qin-Er
(Laboratory of S ystematic and Evolut ionary Botany , Insti tu te of Botany , the Chinese Academy of Sciences , Beijing 100093)
Abstract　Actaea asiatica was previously reported to have the most symmetric and primit ive
karyo type , consisting of 10 m- and 6 sm-chromosomes , which is qui te dif ferent from those of
the remaining species in the genus Actaea , consisting of 10 m-, 4 sm- and tw o T-
chromosomes.In this paper , the chromosomes of this species w ere re-examined.The results
show that Actaea asiatica has the same karyotype as the other species in the genus.
Compared with the species in other genera in the t ribe Cimicifugeae , i.e.Beesia ,
Anemonopsis , Souliea and Cim ici fuga , Actaea asiat ica , together wi th the remaining
species of the genus , has the most asymmetric and thus probably the most advanced
karyo type in this tribe because of the presence of tw o T-chromosomes in thei r chromosome
complements.The tw o T-chromosomes may serve as one of the most impo rtant cy tological
markers , by which the species in Actaea are clearly distinguishable cytologically from those
in Beesia , Anemonopsis , Souliea and Cim ici fuga.
Key words　Actaea asiat ica;Karyo type;Ranunculaceae
Actaea L.is a small genus of eight species in the Ranunculaceae (Tamura , 1995).All
the species have been cy tologically studied and found to have the same chromosome number
of 2n=16 (Wang et al., 1994;Kurosaw a , 1979;Kawano et al., 1966;Kurita , 1959 ,
1957).Their karyotypes are also essentially uniform , consisting of 10 large m-, 4
moderately large sm- and 2 smaller T-chromosomes.The smallest pair of T-chromosomes ,
which have no sho rt arms , are very remarkable and may serve as one of the most important
cytological markers of the genus , by which the species in this genus can be clearly
distinguished cy tologically from the o ther species in the tribe Cimicifugeae , which , besides
Actaea , includes Beesia , Anemonopsis , Souliea , Cimicifuga(W.T .Wang , 1979).In the
lat ter 4 genera , the smallest pair of chromosomes have very short but always clearly
observable short arms(Yang , 1995;Hasegaw a &Peng ,1991;Hasegaw a ,1970a ,b , c , 1969;
Kurita ,1957).However , the karyotype of A.asiatica was repeatedly repo rted to comprise
10 m- and 6 sm-chromosomes , with the smallest pai r having submedian centromeres(Wang
et al., 1994;Kuri ta , 1957).This result has unfortunately led Wang et al.(1994) to
consider that A.asiatica is cytologically qui te distinct from its close relative , A .
中国科学院资源与环境重点项目资助的课题。
1998-08-17收稿 , 1998-10-06收修改稿。
植 物 分 类 学 报　36(6):490～ 495(1998)
Acta Phytotaxonomica Sinica
erythrocarpa ,which has the karyotype of 10 m-, 4 sm- and 2 T-chromosomes , and more
seriously , further led Kurita(1958)and Tamura (1995)to believe that A .asiat ica might
have the most symmetric and thus the most primit ive karyotype in the Ranunculaceae ,
although simultaneously Tamura felt a lit tle confused about this result and pointed out that i t
is far from understandable , because A.asiatica has as the o ther species in the genus the
same berry-like follicles , a very specialized g ross-morphological character of the genus w hich
indicates its advanced position in the t ribe Cimicifugeae.As is w ell-known , the other 4
genera, i.e.Beesia , Anemonopsis , Soul iea and Cim ici fuga , all have typical follicles ,
which are usually regarded as a primitive character.Having studied the chromosomes of the
Ranunculaceae for many years and found that the chromosome mo rphology in a same genus in
this family is of ten basically quite uniform , I guess that Kurita s and Wang et al. s reports
of the kary otype of A.asiatica mentioned above are most probably w rong .As seen from
their papers , the chromosomes in their preparations are no t so well-spread and the
chromosome morphology is not good enough to allow making exact karyotypic analysis.In
o rder to confirm my conjecture , the chromosomes of this species w ere here re-examined.
1　Materials and Methods
Two populations , one from Huadianba , Cangshan Mountain , Dali City , Yunnan
Province , the other from Yezhi , Yunling Mountain , Weixi County , also Yunnan Province ,
were collected f rom the field and then transplanted to the greenhouse of the Botanic Garden ,
Kunming Inst itute of Botany , the Chinese Academy of Sciences.The voucher specimens ,
Yang Qin-er 9430 and 9477 , were deposi ted in the Herbarium , Insti tute of Bo tany , the
Chinese Academy of Sciences(PE).
For the observation of the chromosomes , actively growing roots w ere harvested and then
pret reated with 0.1% colchcine for 2.5 hours at room temperature.They were then f ixed in
Carnoy s f luid (absolute ethanol∶g lacial acetic acid=3∶1)at 4 ℃ for 30 minutes.After
being macerated in the mix ture of 1 mol/ L HCl and 45% acetic acid at 60 ℃ fo r three
minutes , they were stained in 1% aceto-o rcein and squashed.
Karyomorphological classification of resting nuclei and mitotic prophase chromosomes
followed Tanaka (1977 , 1971).The symbols for the descript ion of karyotypes follow ed
Levan et al.(1964).
2　Results
In resting nuclei (Fig.1:A), numerous chromocenters were observed.The other
regions w ere also stained well but unevenly.Thus , the resting nuclei w ere categorized as the
complex chromocenter type.
In prophase chromosomes (Fig.1:B), hetero- and euchromatic segments w ere
distinguishable but their boundaries were no t distinct and the heterochromatic segments w ere
distributed in the distal and interstitial as well as proximal regions.Thus , the prophase
chromosomes w ere categorized as the interstitial type.
The metaphase chromosomes of bo th populations w ere counted to be 2n=16(Fig.1:C ,
D , E , F).Their karyo types w ere very similar and w ere formulated as 2n=10m(3sat)+4sm
+2T(Table 1).Five pairs(the fi rst , the second , the third , the fourth and the fif th)of
chromosomes were quite large and had median centromeres , and two pairs(the sixth and the
seventh)were moderately large and had submedian centromeres , and the last and smallest
pair had no short arms and thus belonged to T-chromosomes.The fi rst , the fif th and the
six th chromosomes had relatively large satellites on the short arms.
6 期 杨亲二:类叶升麻具有毛茛科中最对称和最原始的核型吗? 491　
Table 1　Parameters of chromosomes in two popula tions of Actaea asiatica
Chromosome
No.
Population f rom Dali(Yang Qin-er 9430) Population f rom Weixi(Yang Qin-er 9477)
Relat ive
length
Arm
ratio
Type
Relat ive
length
Arm
ratio
Type
1 4.59+3.65=8.24 1.26 m＊ 4.18+3.67=7.85 1.14 m＊
2 4.42+3.53=7.95 1.25 m 4.18+3.67=7.85 1.14 m
3 4.06+3.77=7.83 1.08 m 4.05+3.54=7.59 1.14 m
4 4.14+3.61=7.75 1.15 m 4.18+3.29=7.47 1.27 m
5 3.98+3.73=7.71 1.08 m＊ 3.92+3.54=7.46 1.11 m＊
6 3.65+3.25=6.90 1.12 m＊ 3.92+3.54=7.46 1.11 m＊
7 3.65+3.04=6.69 1.20 m 3.80+3.04=6.84 1.25 m
8 3.65+2.84=6.49 1.29 m 3.80+3.04=6.84 1.25 m
9 3.81+2.64=6.45 1.44 m 3.54+2.78=6.32 1.27 m
10 3.45+2.80=6.25 1.23 m 3.54+2.78=6.32 1.27 m
11 3.49+2.03=5.52 1.72 sm 3.67+2.03=5.70 1.81 sm
12 3.41+1.78=5.19 1.92 sm 3.67+2.03=5.70 1.81 sm
13 3.04+1.42=4.46 2.14 sm 3.04+1.52=4.56 2.00 sm
14 3.04+1.42=4.46 2.14 sm 2.66+1.52=4.18 1.75 sm
15 4.02+0.00=4.02 ∞ T 3.92+0.00=3.92 ∞ T
16 3.94+0.00=3.94 ∞ T 3.92+0.00=3.92 ∞ T
　＊ indicates sat-ch romosomes.The length of satellit es i s included in short arms.
3　Discussion
The present results clearly show that the karyo type of Actaea asiat ica has basically the
same karyotype as the other species in this genus , and the smallest pair of chromosomes have
no sho rt arms.Thus we can safely say that bo th the result of karyo typic analysis of Actaea
asiatica reported by Kuri ta(1957)and that by Wang et al.(1994)are w rong.They all
mistakenly recognized the smallest pair as sm-chromosomes due to the poor quality of their
chromosome preparations on the one hand , and perhaps more importantly , due to their
lacking of an overall understanding of the chromosome morphology and gross-morpholoical
characters of the Ranunculaceae.If they had known that in the Ranunculaceae the
chromosome morphology in a same genus is of ten uniform , which actually is the reason why
the chromosomal evidence is of utmost importance to determine the systematic positions of
the genera in the family as repeatedly st ressed by Tamura(1995 ,1984), and that the genus
Actaea is phy logenetically very specialized in the family as indicated by its having berry-like
follicles , such mistakes should have been avoidable.Indeed , in cy totaxonomic research of
plants , the importance of high-quality chromosome preparations and a comprehensive view of
the chromosomal and gross-morphological characterist ics of the group under question canno t
be too highly emphasized.
As mentioned above , the t ribe Cimicifugeae includes five genera , i.e.Beesia ,
Anemonopsis , Souliea , Cimici fuga and Actaea and all of them have been cytologically
studied.In general , they have very similar karyomorphological characteristics compared w ith
the other groups in the Ranunculaceae.Their chromosomes are qui te large , w ith the f ive
largest pairs having median or submedian centromeres , the two moderately large pairs having
submedian or subterminal cent romeres depending on the species , and the smallest pair having
492　 植　物　分　类　学　报 36 卷
Fig.1　Photomicrographs of rest ing nuclei , prophase chromosomes and metaphase chromosomes
in tw o populat ions of Actaea asiat ica Hara
A , B , C and E———populat ion f rom Dali(Yang Qin-er 9430);D and F——— population f rom Weixi(Yang Qin-er 9477).
A.rest ing nuclei;B.prophase chromosomes;C ～ F.metaphase chromosomes.
(all ×1940;the arrows indicate the secondary constrict ions.)
short but alw ay s clearly observable arms and terminal centromeres(in Beesia , Anemonopsis ,
Souliea and Cimici fuga), or simply having no short arms(in Actaea).In the
Ranunculaceae , such combinations of kary otypic characters are only found in this t ribe.It is
also noteworthy that the secondary const rictions seem to much more f requently appear in this
tribe, particularly in the genus Actaea , than in the o ther groups of the Ranunculaceae.
6 期 杨亲二:类叶升麻具有毛茛科中最对称和最原始的核型吗? 493　
Hence , karyomo rphologically the t ribe Cimicifugeae is fairly isolated in the family .Based on
the evidence from serology , phy tochemist ry and palynology respectively , Hammond(1952),
Hsiao (1980)as well as Wang et al.(1993)all contended that this tribe should be better
removed from the subfamily Helleboroideae and established as a separate subfamily , i.e.
Cimicifugoideae.This view point is st rong ly suppo rted by karyomorphological data.
In the Ranunculaceae , Cimici fuga may be the closest relative of Actaea.The former
has typical follicles but the lat ter has specialized berry-like follicles.Cy tologically Cimici fuga
has tw o st-chromosomes but Actaea has tw o T-chromosomes.It seems that both gross-
morphologically and cytologically Actaea may be more specialized than Cimici fuga.
From the above analyses , it can be concluded that Actaea asiatica has basically the same
karyo type as the other species in the genus Actaea , and its smallest pair(the eighth pai r)of
chromosomes have no short arms.Compared wi th the species in o ther genera of the t ribe
Cimicifugeae , Actaea asiat ica , together w ith the remaining species in the genera , has the
most asymmetric and thus probably the most specialized karyotype in the t ribe , instead of the
most symmetric and primi tive one.The specialized karyotypic character of this genus might
be correlated to some deg ree w ith i ts specialized gross-morphological character , the berry-like
follicles.
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摘要　根据以前的报道 ,类叶升麻 Actaea asiatica Hara具有 10 条大型的中部着丝点染色体和 6 条较大
的近中部着丝点染色体 ,其核型在毛茛科中显得最为对称和原始 , 而类叶升麻属的其他种类具有 10 条
大型的中部着丝点染色体 、 4 条较大的近中部着丝点染色体和两条没有短臂的染色体 。在毛茛科中 , 同
一属的染色体形态通常十分相似 ,因此上述类叶升麻的核型分析结果十分可疑。本文重新检查了该种
的染色体。结果表明其核型与该属其他种类的核型没有明显区别。 与升麻属其他 4 属 , 即 Beesia ,
Anemonopsis , Souliea , Cimicif uga 相比 , 类叶升麻及该属其他种类都具有两条没有短臂的 T 染色体 , 因
此类叶升麻属 Actaea L.的核型不对称性程度在升麻族中显得最高 , 其核型在该族中也可能最为进化。
这两条 T 染色体可以作为类叶升麻属的细胞学标志 ,据此可以将该属与升麻族其他 4属区别开来 。
关键词　类叶升麻;核型;毛茛科
6 期 杨亲二:类叶升麻具有毛茛科中最对称和最原始的核型吗? 495