作 者 ：Fu Cheng-Xin, Hong De-Yuan
期 刊 ：植物分类学报 1990年 3期
关键词：核型细胞分类菝葜属中国；
Keywords:Karyotype, Cytotaxonomy, Smilax, Zhejiang, China,
Abstract:
The chromosome numbers and karyotypes of 7 species of Smilax L. in Lilia-
ceae (s. 1.) are cytotaxonomically studied in this work. Their karyotypic characters, distinc-
tion between the species and the chromosomal basis of sexual differentiation are discussed. The
karyotypes of most species are first reported. The results are shown as follows (see Tables
1-4 for the chromosome parameters and the karyotype constitution; Fig. 1 for their idio-
grams):
1. Smilax nipponica Miq. The species is one of the herbaceous species distri-
buted in East Asia. Two karyotypes, 2n = 26(type A) and 2n = 32 (type B), are
found in the species (Plate 1: 1-7). The karyotype of No. 88032 (uncertain of
-L- -M- -S-
sexuality) is 2n = 26 = 2m + 6st + 6m + 4sm + 6sm + 2st. The karyotype has 4
pairs of L chromosomes, of which the first three pairs are subterminal, and the 4th
is median. The karyotype belongs to 3B. No. 88045 (the male) and No. 88046
(the female) have 2n = 32. Their karyotypes are basically uniform, and both are
-L- -M- - S
2n=32= 2m+4sm+ 2st+ 2m+4sm+ 6m+ 10sm + 2st, also with 4 pairs of L
chromosomes, but the 2nd pair is median, and thus different from the type A. The
karyotype belongs to 3B. The first pair of chromosomes of the male are distinctly
unequal in length, with the D. V. (0.93) of relative length between them obviously
greater than that of the female (0.1). The pair seems to be of sex-chromosomes.
Sixteen bivalents (n= 16) were observed at PMCs MI of No. 88045 (Plate 1: 4).
The major difference between the karyotypes A and B are greater relative length
of L chromosomes in the type A than in the type B, and the increase of chromoso-
me number in the karyotype B mainly due to the increase of st chromosomes. Na-
kajima (1937)reports 2n= 30 for S. hederacea var. nipponica (=S. nipponica,
Wang and Tang, 1980).
2. S. riparia A. DC. This species is also herbaceous, distributed in East Asia.
Thirty chromosomes were found in root-tip cells (uncertain of sexuality). The kar-
-L- -M- -S
yotype is 2n = 30 = 8st + 6sm + 2st + 6m + 6sm + 2st (Plate 3: 1, 5), consisting
mainly of sm and st chromosomes. There are 4 pairs of L chromosomes which are
all subterminal and the m chromosomes appear to fall all into S category. Though
the karyotype belongs to 3B, it is less symmetrical than that of S. nipponica. The
species is karyologically rather different from S. nipponica, therefore. The first pair
of chromosomes of this material are unequal in length, and it may be a male. The
karyotype of this species is first reported.
3. S. sieboldii Miq. The species is a thorny climbing shrub, distributed in
East Asia. At PMCs All, 16 chromosomes (n= 16) were found (Plate 2: 6), in
accordance with Nakajima‘s (1933) report for a Japanese material.
4. S. china L. This species, a thorny climbing shrub, is of a wide distribu-
tion range mainly in East Asia and Southeast Asia. Two karyotypes were observed
in different populations. (1) The population from Xikou has 2n = 96(6x) = 20st+
L- -M-
6t + 6sm + 12st + 52(S) (Plate 3:7), of which the first three pairs of chromo-
somes are terminal, different from those in the other species. The arm ratios of
both L and M chromosomes are larger than 2.0, which resembles those of S. davi-
diana. (2) PMCs MI of the population from Shangyu shew 15 chromosomes (n
15). The hexaploid of the species is recorded for the first time. Hsu (1967,1971)
reported 2n = 30 from Taiwai and Nakajima (1937) recorded n = 30 from Japan,
which indicates that the karyotype of the species varies not only in ploidy, but
also in number.
5. S. davidiana A. DC. The somatic cells were found to have 32 chromoso-
mes, and PMCs MI shew 16 bivalents (Plate 2: 1-5). The karyotype is 2n = 32=
-L- -M- -S
8st + 4sm + 4st + 8sm + 8st. The karyotype belongs to 3B, and is less symmetri-
cal than those in herbaceous species. The D. V. (0.20) of relative length between
the two homologues of the first pair is slightly larger in the male than in the fe-
male (0.14), and it is thus difficult to determine whether they are sexual chromos-
omes or not.
6. S. glabra Roxb. The species is a non-thorny climbing shrub, distributed
in East Asia and Southeast Asia. 32 chromosomes were found in somatic cells. The
-L- -M- - S-
karyotype is 2n= 32= 8st + 10st+6sm+8st (Plate 3: 2, 6),with only 3 pairs
of sm chromosomes (12, 13 and 16th). The karyotype is more asymmetric than
that of S. davidiana, although it is also of 3B (Table 1). The karyotype is first
reported for the species.
7. S. nervo-marginata Hay. var. liukiuensis (Hay.) Wang et Tang The variety
has a relatively narrow distribution range, mainly occurring in eastern China. The
chromosomal number of somatic cells is 2n= 32 (Plate 3: 3-4). The karyotype is
-L- -M- -S
2n = 32 = 2sm + 6st + 2sm + 2st + 2m + 6sm + 12st, evidently different from that
of S. glabra. The first pair of chromosomes are submedian, and much longer than
the 2nd to 4th pairs. The ratio in length of the largest chromosome to the smallest
one is 4.3. The symmetric degree is of 3C, a unique type. The karyotype of the
species is reported for the first time.
In Smilax, the known basic numbers are 13, 15, 16 and 17. The two herbaceous species
distributed in East Asia have three basic numbers: 13, 15 and 16, while the woody species studi-
ed mainly have 16, with no 13 recorded. Mangaly (1968) studied 8 herbaceous species in North
America and reported 2n=26 for them except S. pseudo-china with 2n=30. Mangaly consi-
dered that a probably ancestral home of Smilax, both the herbaceous and woody, is in Southeast
Asia and the eastern Himalayas, and speculated that the ancestral type of Sect. Coprosman-
thus is possibly an Asian species, S. riparia. The karyotypes of the two herbaceous species in
East Asia consist mostly of sm and m chromosomes, whereas those for the North American
species are all of st chromosomes. Based on the general rule of karyotypic evolution, i.e. from
symmetry to asymmetry, his speculation seems reasonable.
Researches on sex-chromosomes of Smilax have been carried out since 1930 (Lindsay, 1930;
Jensen, 1937; Nakajima, 1937; Mangaly, 1968), and they are generally considered to be the
largest pair, but there is still no adequate evidence. The result of our observation on S. nipponica
may confirm that the first pair of chromosomes of this species is XY type of sex-chromosomes.
Chromosomes of the genus are small and medium-sized, varying between 1-6 μm, slightly
larger in herbaceous species than in woody ones, larger in the karyotype of 2n=26 than in
that of 2n=32. Based on karyotype constitution of the above 5 species, the karyotype in the
genus is characterized by 4 pairs of L chromosomes and 2-5 pairs of M chromosomes, and
mostly st and sm chromosomes, and by rather asymmetrical 3B type. The degree of symmetry
in the above 5 species is from Sect. Coprosmanthus to Sect. Coilanthus, and herbaceous species to
woody ones.