Structural Differences in Chromosomes Distinguish Species in the Tomato Clade
Structural Differences in Chromosomes Distinguish Species in the Tomato Clade
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DOI：
10.1159/000313850
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发表时间：
2010-01-01
影响因子：
1.7
通讯作者：
Stack, S. M.
中科院分区：
文献类型：
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作者：
Anderson, L. K.;Covey, P. A.;Stack, S. M.
茄科番茄枝由12种具有相同染色体数目和形态的二倍体组成。由于F-1杂交种中的粗线染色体通常沿着它们的长度突触，而且种内和种间杂交种的连锁图谱是共线性的，因此人们认为番茄枝中的物种主要是通过基因变化而不是大规模的染色体重排而进化的。然而，据报道，番茄和它的一些野生近缘种之间存在小的反转。因此，我们使用高分辨率电子显微镜检查粗线染色体（=突触复合体）扩散，重新评估了5个F-1杂交种，以确定在番茄进化枝的物种之间是否发生了任何微小的结构变化，这些变化在常规染色体挤压的光镜分析中不容易看到。我们的研究揭示了一些意想不到的突触结构，如不匹配的着丝点、反转环和相互易位。这些结构差异大多位于或靠近异染色质，而异染色质的基因相对较少，重组较少，因此它们对连锁图谱的明显共线性影响不大，特别是在常染色质中。然而，这些结果表明，染色体结构的实质性变化已经发生在物种之间的番茄分支。版权所有：S. Karger AG，巴塞尔
The tomato clade of Solanaceae is composed of 12 species that are all diploid with the same chromosome number and morphology. Species in the tomato clade are considered to have evolved primarily by genic changes rather than large-scale chromosomal rearrangements because pachytene chromosomes in F-1 hybrids synapse normally along their lengths and linkage maps of intra- and inter-specific hybrids are co-linear. However, small inversions have been reported between tomato and some of its wild relatives. Therefore, we reevaluated 5 F-1 hybrids using high-resolution, electron microscopic examination of pachytene chromosome (= synaptonemal complex) spreads to determine whether any minor structural changes had occurred among species in the tomato clade, which were not easily visible using light microscopic analysis of conventional chromosome squashes. Our study revealed a number of unexpected synaptic configurations such as mismatched kinetochores, inversion loops and reciprocal translocations. Most of these structural differences were in or close to heterochromatin that has comparatively few genes and little recombination, so they would be expected to have little effect on the evident colinearity of linkage maps, especially in euchromatin. However, these results demonstrate that substantial changes in chromosome structure have occurred among species within the tomato clade. Copyright (C) 2010 S. Karger AG, Basel