Chromosome arrangement and behaviour of two rye homologous telosomes at the onset of meiosis in disomic wheat-5RL addition lines with and without the Ph1 locus
Chromosome arrangement and behaviour of two rye homologous telosomes at the onset of meiosis in disomic wheat-5RL addition lines with and without the Ph1 locus
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DOI：
10.1023/a:1021564327226
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发表时间：
2002-11-01
影响因子：
2.6
通讯作者：
Naranjo, T
中科院分区：
文献类型：
--
作者：
Maestra, B;de Jong, JH;Naranjo, T
采用荧光原位杂交技术（FISH）对六倍体黑麦5RL双中心附加系的小孢子细胞进行了总基因组和重复DNA的检测，研究了黑麦同源染色体臂在减数分裂前间期和减数分裂前期的行为与着丝粒和端粒动力学的关系。通过比较有和没有Ph1位点的等基因系，我们确定了Ph1基因对黑麦染色体外观和行为的影响。Ph1和ph1b系表现出相似的减数分裂前染色体排列，尽管存在着丝粒关联，但两个黑麦同源物占据分开的结构域。我们的研究证实了端粒的束状排列遵循Rabl结构。在端粒呈束状聚集的细胞中，5RL端粒的着丝粒仍然在相反的极，表明着丝粒锚定在细胞骨架上。一旦端粒完成聚集，黑麦着丝粒迁移到端粒极点，黑麦染色体开始松动其结构。虽然野生型的黑麦同源物在细胞核中保持单独的区域，但它们在ph1b突变体中变得混合，可能是因为它们的冷凝率较低。在随后的阶段，5RL同源物主要在远端区域密切相关。我们的研究表明，ph1b突变体的染色体突触率较低是由于染色质去浓缩和组织异常所致。
Fluorescence in- situ hybridization ( FISH) of total genomic and repetitive DNA on microsporocytes of ditelocentric addition lines of rye 5RL in hexaploid wheat was performed to study the behaviour of the rye homologous chromosome arms in relation to centromere and telomere dynamics at premeiotic interphase and meiotic prophase I. By comparing isogenic lines with and without the Ph1 locus, we established the effect of the Ph1 gene on appearance and behaviour of the rye chromosomes. Ph1 and ph1b lines demonstrated similar premeiotic chromosome arrangement with the two rye homologues occupying separated domains despite the occurrence of centromere association. Our study confirmed that bouquet arrangement of telomeres follows the Rabl configuration. In cells displaying bouquet clustering of telomeres, centromeres of the 5RL telosomes are still at the opposite pole, suggesting anchoring of centromeres at the cytoskeleton. Once the telomeres complete clustering, the rye centromeres migrate to the telomere pole, and the rye chromosomes begin to loosen their structure. While the rye homologues in the wild- type keep separate territories in the nucleus, they become intermingled in the ph1b mutant, possibly because of their lower condensation. In a subsequent stage, the 5RL homologues appear intimately associated mainly at the distal region. Our study suggests that the lower rate of chromosome synapsis in the ph1b mutant results from abnormal chromatin decondensation and organization.