全 文 ：蜘蛛抱蛋属植物的核型不对称性分析 ?
乔 琴1 , 2 , 张长芹1
??
, 马永鹏1 , 2 , 田 伟1 , 2
( 1 中国科学院昆明植物研究所 , 云南 昆明 650204; 2 中国科学院研究生院 , 北京 100049 )
摘要 : 报道了蜘蛛抱蛋属 ( Aspidistra) 两种植物的染色体数目和核型 , 其中河口蜘蛛抱蛋 ( A. hekouensi )
的染色体数目 (2 n= 38) 为首次报道 , 四川蜘蛛抱蛋 ( A. sichuanensis) 染色体数目也为 2 n= 38 , 但其核型
与以往的报道有差别。使用染色体内不对称系数 (A1 ) 和染色体间不对称系数 (A2 ) 对该属 34 种植物核
型的不对称性进行了分析 , 结果表明该属植物的核型似乎并没有向不对称性增强的方向演化。
关键词 : 蜘蛛抱蛋 ; 核型不对称性 ; 染色体内不对称系数 ; 染色体间不对称系数
中图分类号 : Q 942 文献标识码 : A 文章编号 : 0253 - 2700 (2008) 05 - 565 - 05
Karyotype Asymmetry of Aspidistra (Convallarieae , Ruscaceae)
QIAO Qin
1 , 2
, ZHANG Chang-Qin
1 * *
, MA Yong-Peng
1 , 2
, TIAN Wei
1 , 2
(1 Kunming Instituteof Botany, ChineseAcademy of Sciences, Kunming 650204 , China;
2 GraduateUniversity of Chinese Academy of Sciences, Beijing 100049 , China)
Abstract: Two species of Aspidistra fromYunnan, China, were cytologically studied . The chromosome number of A. h-
ekouensis, 2 n= 38 , is reported for the first time . The chromosome number of A. sichuanensis, also 2 n= 38 , was consis-
tent with earlier reports, but the karyotype differs fromthe previous report . Furthermore, we used two numerical parame-
ters, A1 ( intrachromosomal asymmetry index) and A2 ( interchromosomal asymmetry index) , to estimate the karyotype
asymmetry in 34 species of . The results showed that there is no predominant trend towards an increasing of asymmetry of
the karyotype in Aspidistra .
Key words: Aspidistra; Karyotype asymmetry; Intrachromosomal asymmetry index; Interchromosomal asymmetry index
The genus Aspidistra, formerly treated in the
Convallariaceae, is now in the family Ruscaceae ( Ru-
dall et al. , 2000; APGII , 2003 ) . Species in this ge-
nus aremostly distributed in South-east Asia . Thetotal
number of species in Aspidistra is 76 species ( Tillich,
2005) , 51 of which are known fromChina . According
to cytological data of 38 species, two different basic
chromosome numbers appear within the genus: x= 18
and x = 19 , and both of them approximately encom-
passes50% species in the published data ( Wang et
al. , 2001 ) . There has been debate about which basic
number is ancestral one, that is, chromosome number
has increased or decreased during evolution in Aspidis-
tra (Hong et al. , 1986; Huang et al. , 1997; Wang et
al. , 2001; Yamashita and Tamura, 2004 ) . Based on
the analysis of karyological asymmetry and morphologi-
cal characters, Wang (2001 ) proposed that species in
x= 18 were ancestor and have higher karyotype asym-
metry than species in x= 19 , but their result was lack
of quantitative analysis . On the contrary, we consider it
would bemore reasonable toassume that species in x=
18 of Aspidistra was derived from an ancestral x = 19
云 南 植 物 研 究 2008 , 30 (5) : 565～569
Acta Botanica Yunnanica DOI : 10 .3724?SP. J . 1143 .2008.08008
?
?? ?Author for correspondence ; E-mail : zhangchangqin@ mail . kib. ac. cn
Received date: 2008 - 01 - 26 , Accepted date: 2008 - 06 - 27
作者简介 : 乔琴 ( 1981 - ) 女 , 在读博士研究生 , 主要从事开口箭的保护生物学研究。 ?
Foun ?dation items: The National Natural Science Foundation of China (30571137 , 30770139 ) and The Ministry of Science and Technology of China
(2005DKA21006 )
according to the result of Yamashita and Tamura
( 2004) . Romero (1986) proposed an alternativemeth-
od for measuring the karyotype asymmetry by using
quantification and graphic representation, and two nu-
merical parameters ( A1 = intrachromosomal asymmetry
index and A2 = interchromosomal asymmetry index)
were introduced in analyzing patterns of karyotype
asymmetry .
In the present studyweundertook a cytotaxonomic
analysis of A. hekouensis and A. sichuanensis in Yun-
nan, China, and analysed the karyotype asymmetry of
Aspidistra following Romero′s method, and discussed
the evolutional trendsof karyotype asymmetry in thege-
nus .
Materials and Methods
Aspidistra sichuanensis and A. hekouensis were collected
from the Botanical Garden of Kunming Instituteof Botany (Table
1) . Voucher specimens are deposited in the Herbarium of Kun-
ming Institute of Botany, the Chinese Academy of Sciences
(KUN) . Cells of root tips were used for chromosome count and
karyotype analysis . Root tips were pretreated in 2 mmol?L
hydroxyquinoline at room temperature for 4 - 5 hours, and then
fixed in Carnoy solution (ethanol: acetic acid= 3∶1) at 4℃ for
18 hours . After maceration in 1N hydrochloric acid at 60℃ for
10 minutes, material was stained with Carbol Fuchsin and
squashed for observation in 45% acetic acid . Five individuals
were investigated for each species . Chromosome measurements
were obtained from the photographs of the best 5 mitotic met-
aphase plates . Terminology for position of centromeres on chro-
mosomes follows Levan et al. ( 1964 ) , and karyotypes following
theclassification of Stebbins (1971) .
The intrachromosomal ( A1 ) and interchromosomal ( A2 )
asymmetry indices were calculated according to Romero Zarco
(1986) . Thedata of relativechromosome length ( including short
arms and long arms) were obtained from previous cytological
studies (Hong et al. , 1986; Huang et al. , 1997 ; Wang et al. ,
1999; Wang et al. , 2000; Wang et al. , 2001) .
Results
Aspidistra hekouensis
The species A. hekouensis was investigated for the
first time . The chromosome number is 2 n = 38 , with
thekaryotype formulaof 22m+ 2sm+ 14st . Pair 9th is
sm- type chromosomes, pairs 2nd-8th arest-type, other
pairs are m-type . No satellites were observed in our
study . The chromosomes showed a trimodal variation in
length . Pair 1st is long chromosomes, while the num-
ber of pairsof themediumandshort chromosomes are 7
and 11 pairs respectively . The ratio of the longest to
the shortest chromosomes is 4.63∶1 , and thekaryotype
symmetry is 2C (Table 2; Fig . 1 : A , C) .
Aspidistra sichuanensis
The chromosome number of A. sichuanensis is 2 n
= 38 , with the karyotype formulaof 2 n= 38 = 21m+
7sm+ 12st . Pairs 9th, 17th and one of pair 4th are
sm-type chromosomes, pairs2nd, 3rd, and 5th-8th are
st-type, others are m-type . The chromosomes of the
fourth pair differ significantly in their length, which
have median centromeres ( m-type) and submedian
centromeres (sm-type) respectively . No satellites were
observed in the present study . The chromosomes
showed a trimodal variation in length . Pair 1st is long
chromosomes, whilethe number of pairsof themedium
and short chromosomes are7 and 11 pairs respectively .
The ratio of the longest to the shortest chromosomes is
6 .13∶1 , and the karyotype symmetry is 2C ( Table 2;
Fig . 1 : B , D) . The karyotypeof this species differed
fromthose reported earlier ( i . e ., 2 n = 38 = 24m+
4sm+ 10st (2SAT) ( Wang et al. , 2000 ) , and 2 n =
38 = 22m+ 4sm (2SAT ) + 12st (Hong et al. , 1986) .
2 n= 38 = 22m+ 4sm ( 2SAT ) + 12st + 5B , 2 n = 38
= 20m+ 6sm+ 12st (2SAT) ( Huang et al. , 1997) .
The intrachromosomal asymmetry index ( A1 ) and
the interchromosomal asymmetry index (A2 ) were cal-
culated based on thedata available for 34 species (Ta-
ble 3) , including16 species in 2 n= 36 and 19 species
in 2 n= 38 . A1 varied from0.41 to 0.51 in 2 n= 36 and
0.36 to 0.54 in 2 n= 38; A2 varied from0.51 to 0.66 in
2 n= 36 and 0 .52 to 0 .69 in 2 n= 38 . The varianceof
Table 1 Species of Aspidistra examined, their vouchers and karyotype formula
Species Collection Karyotype Type
Aspidistra hekouensis Hekou, Yunnan, China, Qiao qin 200702 ?2 |n= 38 = 22m+ 2sm (2SAT ) + 14st 2 ?C
A ?. sichuanensis Kunming, Yunnan, China, Qiao qin 200703 ?2 |n= 38 = 20m+ 6sm (2SAT ) + 12st 2C
Vouchers are deposited in the herbarium of the Kunming Institute of Botany ( KUN)
665 云 南 植 物 研 究 30 卷
Table 2 The parameters of chromosomes of A. hekouensis and A. sichuanensis
Aspidistra sichuanensis
No . Relative length Ratio Type
Aspidistra hekouensis
No . Relative length Ratio Type
1 ?2 .94 + 3 .37 = 6 .31 1 . 15 m 1 ?2 9. 77 + 3 .44 = 6 .21 1 5. 24 m
2 ?0 .74 + 4 .02 = 4 .76 5 . 43 st 2 ?0 9. 67 + 3 .37 = 4 .04 5 5. 03 st
3 ?0 .98 + 3 .68 = 4 .66 3 . 76 st 3 ?0 9. 67 + 3 .3 = 3 .97 4 5. 93 st
4 ?1 .28 + 3 .14 = 4 .42 2 . 45 sm 4 ?0 9. 67 + 3 .24 = 3 .91 4 5. 84 st
5 ?0 .64 + 3 .39 = 4 .03 5 . 30 st 5 ?0 9. 67 + 3 .03 = 3 .7 4 5. 52 st
6 ?0 .64 + 3 .24 = 3 .88 5 . 06 st 6 ?0 9. 67 + 2 .9 = 3 .57 4 5. 33 st
7 ?1 .07 + 2 .80 = 3 .73 2 . 62 sm 7 ?0 9. 54 + 3 .03 = 3 .57 5 G. 6 st
1 ?. 59 + 2 .14 = 3 .73 1 . 34 m
8 ?0 .54 + 2 .16 = 2 .70 4 . 00 st 8 ?0 9. 54 + 2 .7 = 3 .24 4 5. 99 st
9 ?0 .59 + 1 .42 = 2 .01 2 . 41 sm 9 ?0 9. 67 + 1 .42 = 2 .09 2 5. 12 sm
10 ?0 .69 + 0 .88 = 1 .57 1 . 28 m 10 !0 9. 81 + 0 ?. 94 = 1 .75 1 5. 16 m
11 ?0 .69 + 0 .83 = 1 .52 1 . 20 m 11 !0 9. 81 + 0 ?. 94 = 1 .75 1 5. 16 m
12 ?0 .59 + 0 .79 = 1 .38 1 . 34 m 12 !0 9. 67 + 1 ?. 08 = 1 .75 1 5. 61 m
13 ?0 .59 + 0 .79 = 1 .38 1 . 34 m 13 !0 9. 67 + 0 ?. 94 = 1 .71 1 G. 4 m
14 ?0 .68 + 0 .69 = 1 .37 1 . 01 m 14 !0 9. 82 + 0 ?. 81 = 1 .63 1 5. 01 m
15 ?0 .68 + 0 .69 = 1 .37 1 . 01 m 15 !0 9. 82 + 0 ?. 81 = 1 .63 1 5. 01 m
16 ?0 .68 + 0 .69 = 1 .37 1 . 01 m 16 !0 9. 67 + 0 ?. 81 = 1 .48 1 5. 21 m
17 ?0 .39 + 0 .79 = 1 .18 2 . 03 sm 17 !0 9. 67 + 0 ?. 74 = 1 .41 1 G. 1 m
18 ?0 .54 + 0 .79 = 1 .33 1 . 46 m 18 !0 9. 68 + 0 ?. 67 = 1 .35 1 5. 01 m
19 ?0 .49 + 0 .54 = 1 .03 1 . 10 m 19 !0 9. 68 + 0 ?. 67 = 1 .35 1 5. 01 m
Fig . 1 Somatic metaphase chromosome and ideograms of somatic metaphase chromosome of two species in Aspidistra
A , C . A. hekouensis; B , D . A. sichuanensis . Bar = 5μm .
A1 and A2 between 2 n= 36 and 2 n= 38 were also an-
alyzed . The results indicated that themean valueof A1
in 2 n= 36 and 2 n= 38 are 0 .46±0 .31 and 0 .44±
0 .48 respectively, which does not vary significantly ( F
7655 期 QIAO Qin et al. : Karyotype Asymmetry of Aspidistra ( Convallarieae, Ruscaceae)
Table 3 Intrachromosomic asymmetry index ( A1 ) and interchromosomic asymmetry index (A2 ) of Aspidistra species
Species
Chromo-
some
counts
Stebb-
ins′s
types
A1 ?A2 References* Species
Chromo-
some
counts
Stebb-
ins′s
types
A1 6A2 ,References*
A ?. fungilliformis 2 n= 36 2C 0 .48 0 .59 Huang et al . 1997 A ]. longiloba 2 n= 38 2C 0 .39 0 . 59 Wang et al . 1999
A ?. longipedunculata 2 n= 36 2C 0 .43 0 .51 Wang et al . 2000b A ]. marginella 2 n= 38 2C 0 .44 0 . 64 Wang et al . 2001
A ?. hainanensis 2 n= 36 2C 0 .42 0 .58 Wang et al . 2001 A ]. leshanensis 2 n= 38 2C 0 .45 0 . 69 Hong et al . 1986
A ?. claviformis 2 n= 36 2C 0 .42 0 .59 Wang et al . 2000a A ]. subrotata 2 n= 38 2C 0 .43 0 . 62 Huang et al . 1997
A ?. yingjiangensis 2 n= 36 2C 0 .51 0 .55 Wang et al . 2001 A ]. hekouensis 2 n= 38 2C 0 .40 0 . 52 the present study
A ?. triloba 2 n= 36 2C 0 .47 0 .60 Huang et al . 1997 A ]. patentiloba 2 n= 38 2C 0 .41 0 . 61 Wang et al . 2000
A ?. dolichanthera 2 n= 36 2C 0 .50 0 .60 Huang et al . 1997 A ]. longanensis 2 n= 38 2C 0 .43 0 . 62 Wang et al . 1999
A ?. ebianensis 2 n= 36 2C 0 .45 0 .62 Wang et al . 2001 A ]. fimbriata 2 n= 38 2C 0 .44 0 . 64 Huang et al . 1997
A ?. muricata 2 n= 36 2C 0 .45 0 .58 Wang et al . 2001 A ]. oblanceifolia 2 n= 38 2C 0 .49 0 . 63 Hong et al . 1986
A ?. lurida 2 n= 36 2C 0 .51 0 .61 Wang et al . 2000a A ]. zongbayi 2 n= 38 2C 0 .45 0 . 66 Hong et al . 1986
A ?. cavicola 2 n= 36 2C 0 .47 0 .61 Wang et al . 2000a A ]. flaviflora 2 n= 38 3C 0 .54 0 . 56 Hong et al . 1986
A ?. retusa 2 n= 36 2C 0 .48 0 .55 Huang et al . 1997 A ]. omeiensis 2 n= 38 2C 0 .48 0 . 60 Hong et al . 1986
A ?. elatior 2 n= 36 2C 0 .41 0 .66 Huang et al . 1997 A ]. caespitosa 2 n= 38 2C 0 .49 0 . 68 Hong et al . 1986
A ?. tonkinensis 2 n= 36 2C 0 .48 0 .61 Huang et al . 1997 A ]. luodianensis 2 n= 38 2C 0 .51 0 . 66 Wang et al . 2000
A ?. saxicola 2 n= 36 2C 0 .47 0 .61 Wang et al . 2001 A ]. minutiflora 2 n= 38 2C 0 .51 0 . 61 Huang et al . 1997
A ?. hexianensis 2 n= 36 2C 0 .47 0 .55 Huang et al . 1997 A ]. cruciformis 2 n= 76 2C 0 .36 0 . 60 Wang et al . 2001
A ?. sichuanensis 2 n= 38 2C 0 .42 0 .63 Huang et al . 1997 A ]. xilinensis 2 n= 76 2C 0 .40 0 . 65 Wang et al . 2001
* Data used in this paper to calculate A1 and A2 obtained from cited cytological studies .
= 1 .87 , P = 0 .181 > 0 .05 ) between the two groups .
As the scatter diagramshows all of thespecies grouped
closely together along theA1 axis (Fig . 2) . However,
it should be noted that themeanvalueof A2 in 2 n= 36
and 2 n= 38 are 0 .59±0.36 and 0 .62±0 .40 respec-
tively . The variance are significant ( F = 6 .86, P =
0 .013 < 0 .05) between the two groups, which indicat-
ed the karyotypes of 2 n = 36 tend to present lower in-
terchromosomal ( A2 ) asymmetry than those of 2 n =
38 . As scatter diagramshows most of thespecies in 2 n
= 38 distributed higher than species in 2 n = 36 along
A2 axis (Fig . 2 ) .
Fig . 2 Scatter diagram showing karyotype asymmetry due to ratio
between arm length ( A1 ) against that due to variation between
chromosome total lengths ( A2 ) . The species in group 2 n= 38
in Aspidistra (○ ) ; the species in 2 n = 36 in Aspidistra (● )
Discussion
Two species of Aspidistra examined by us exhibit-
ed trimodal karyotypeas other species reported in Aspi-
distra . In contrast to an earlier report, in which satel-
lites were considered as a stable character in Aspidistra
(Huang et al. , 1997) , no satellites were observed in
our study . Aspidistra is essentiallya dibasic genuswith
x= 18 and x= 19 . Although there has been debate
about whichbasic number is ancestral one, weconsider
it is reasonable to assume that the x= 19 of Aspidistra
may have been derived from an ancestral x = 18 ac-
cording to the phylogenetic analyses of Yamashita and
Tamura (2004) .
According to thegraphical and quantitative results
(Table 3) , we can see thevariationof intrachromosom-
al asymmetry index ( A1 ) was relatively small between
the two groups, whereas the interchromosomal asymme-
try index (A2 ) in x= 18 is significantly ( F = 6 .86 ,
P = 0 .013 < 0 .05 ) lower than x = 19 . Our results
showed that the ancestral group has higher karyotype
asymmetry than the derived group . It seems that the
tendency for an increase in karyotype asymmetry sug-
gested by Stebbins didn′t present in Aspidistra . Similar
trends of karyotype asymmetry evolution have been re-
ported in gymnosperm and other monocotyledons, such
as Podocarpaceae, Cycadaceae ( Zheng et al. , 2002 )
865 云 南 植 物 研 究 30 卷
and Orchidaceae (Li et al. , 2003 ) . Wang (2001 ) al-
so considered that evolution trends of karyotype in As-
pidistra seemly don′t agree with the tendency of an in-
crease in karyotype asymmetry, but they got the conve-
rseopinion that species in x= 18 have higher karyo-
type asymmetry than species in x = 19 based on the
frequency of m-type chromosomes without quantifiable
analysis . In thepresent paper, only34 speciesoutof 76
species were analyzed, more species should be studied
to obtain authentic phylogenic relationships and reason-
able chromosome evolution hypothesis inthenear future .
Acknowledgements : We thank Professor Li Heng for proving
valuable comments .
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