| 八种国产葱属植物染色体研究 |
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| 引用本文： | 尚宗燕,李汝娟,崔铁成,许介眉.八种国产葱属植物染色体研究[J].中国科学院研究生院学报,1997,35(5):434-444. |
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| 作者姓名： | 尚宗燕 李汝娟 崔铁成 许介眉 |
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| 摘 要： | 本文对国产葱属Allium 8个种的14个居群的染色体进行了研究。其染色体基数均为x=8，其中7个居群为二倍体(2n=2x=16)，6个居群为四倍体(2n=4x=32)，1个居群为多倍体复合体(2n=4x=32，2n=6x=48，2n=8x=64和2n=9x=72)。并发现随体染色体十分活跃，在多倍体中其数目并不都与其倍性相对应，并有“串状随体”现象出现；在有些类群中其形态变异较大，而随体染色体杂合形式的多态现象也较普遍。本文重点讨论了随体染色体的数目、形态变异及杂合现象在葱属进化中的作用，认为随体染色体形态变异及杂合现象的出现是葱属中遗传变异的重要源泉之一。并对葱属中的染色体基数及种内多倍性问题进行了初步讨论。
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| 关 键 词： | 葱属 染色体 随体 多倍性 |
Studies on Chromosomes of Eight Species of Allium from China |
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| Shang Zong-yan,Li Ru-juan,Cui Tie-cheng,Xu Jie-mei.Studies on Chromosomes of Eight Species of Allium from China[J].Journal of the Graduate School of the Chinese Academy of Sciences,1997,35(5):434-444. |
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| Authors: | Shang Zong-yan Li Ru-juan Cui Tie-cheng Xu Jie-mei |
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| Abstract: | Chromosomes of 14 populations of 8 species of Allium from China were observed
in the present work. The results are as follows: (1)A. tuberosum Rottl. ex Spreng: three
populations were studied and they were all tetraploids (2n=4x=32) with 28 m and 4 st on
which satellites usually appeared. The population 1 (C-1237) was found to have the kary-
otype 2n=4x=32=28m+4st(2SAT) (Fig. 1:1 ), the population 2(C-1188) 2n=4x=32=
28m+4st (4SAT) (Fig. 1: 2), and the population 3 (C-1179) with satellites ranging from one to three in number. In some cells we found that the satellites look like a string of beads (Fig.1: 3). (2) A. ramosum L.: the population 1 (C-1193) was diploid with the karyotype 2n =2x = 16 = 14m + 2st ( 2SAT ) ( Fig. 2: 2), while the population 2 (C-1307) was tetraploid with 2n=4x = 32 (Fig. 2:5). The number of sat-chromosomes ranged from zero to three. (3)
A. anisopodium Ledeb.: the population 1 (C-1313) was found to have the karyotype 2n=2x
=16=12m+ 4sm(2SAT) with a pair of terminal satellites ( Fig. 2:1), and the population 2 (C-1286) 2n=2x=16, with the satellite chromosomes exhibiting polymorphism (Fig 5). In
about 80% of cells, a chromosome was found to have a intercalary satellite, and thus the
karyotype became 2n=2x=16=14m+2sm(1SAT) (Fig. 2: 3). (4) A. anisopodium Ledeb. var. zimrmermannianum (Gilg) Wang et Tang (C-1253) was a diploid with 2n=2x=16. One pair of chromosomes had intercalary satellites, which were often detached from the chromosomes (Fig. 2:4). (5) A. nutans L. (C-1312) showed great intrapopulational variation in chromosome number. 2n= 4x=32, 2n=6x=48, 2n=8x=64 and 2n=9x=72 were found in different plants from the same population (Fig. 3: 1, 2, 3). (6) A. macrostemon Bunge(C-1245) had the chromosome number of 2n=4x=32. The satellite chromosomes exhibited polymorphism (Fig.2:6. Fig.5). (7) A. tubifiorum Rendle.: the population 1 (C-1279) was a diploid of 2n=2x= 16 with a pair of chromosomes with terminal satellites ( Fig. 3: 5), and the population 2 (C-1289) a tetraploid with 2n=4x=32,
with two pairs of chromosomes having terminal satellites(Fig. 3:4 ). (8) A. neriniflorum
(Herb.)Baker. The population 1 (C-1318) had the chromosome number of 2n=2x=16 with a pair of chromosomes having intercalary satellites. Non heterozygosity was found in this pair in 1991 (Fig.3: 6), but we found heterozygosity in 1992 (Fig. 3:7 ). The population 2 (C-1393) was also found to have 2n= 2x = 16. The heterozygous satellite chromosomes were found in a few root tips (Fig.3: 8. Fig.5).
Polyploidy is very common in Allium. Seven polyploid populations are reported in this
paper. Some species, such as A. ramosum and A. tubiflorum , had both diploid and tetraploid populations, while some others, such as A. nutans, had different plants respectively with 4x, 6x, 8x and 9x within populations.
We also found that in polyploids the number of satellite chromosomes was not always
correlated with ploidy level. Among the six tetraploids, two populations (C-1188, C-1289)
had four satellite chromosomes, two populations (C-1237, C-1245) had two and the other
two (C-1179, C-1307) had variable number (0～3) of satellites.
Fig. 1: 3 shows bead-like satellites on only one st chromosome among four in tetraploid
C-1179. It is supposed that the satellites of these three st chromosomes were transferred to that one and this“transfer”may lead to unstable number of satellites in polyploids.
Unlike number, the variation of satellite chromosomes in their morphology is more
closely correlated with external morphological characters. In the section Caloscordum, the
diploids of A. tubiflorum and A. neriniflorum have the same karyotype 2n = 2x = 16 =
12m + 4sm(2SAT), but there is a pair of chromosomes with terminal satellites in the for-
mer, while a pair of chromosomes with the intercalary satellites in the latter. Although they are quite similar, they are classified into two species. A similar situation is also found in A. anisopodium (C-1313 with a pair of chromosomes with terminal satellites) and its variety, var. zimmermannianum ( C-1253 with intercalary satellites); the latter has fine teeth on its scape. It is interesting to note that C-1286 seems to have fine teeth, as if this population is an intermediate type, and only one intercalary satellite chromosome is found in more than 80 % of cells. The morphological variation of satellite chromosomes might be one of possible causes leading to speciation.
We consider that the morphological variability and structural heterozygosity of satellitechromosomes are important sources of genetic variation and evolution in Allium. |
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| Keywords: | Allium Chromosome Satellite Polyploidy |
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