Shan Fucheng, Yan Guijun, Plummer Julie A
School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
Genome. 2003 Jun;46(3):507-13. doi: 10.1139/g03-009.
The physical location of the 25S-26S rDNA sequences was examined in 11 taxa of nine species of Boronia. In diploid species, two rDNA sites were detected in Boronia clavata (2n = 14), Boronia pinnata 'White' (2n = 22), and Boronia chartacea (2n = 32); four in Boronia megastigma (2n = 14) and Boronia denticulata (2n = 18); six in Boronia pinnata 'Pink' (2n = 22); and eight in Boronia molloyae (2n = 16). Eleven sites were found in Boronia heterophylla 'Red' and 'Near White' (2n = 15), but only two active nucleolar organizer regions (NORs) were observed. In polyploid species, Boronia pilosa (2n = 44) had four rDNA sites, while Boronia coerulescens (2n = 72) had six. Most of the rDNA sequences were terminal, but a few were interstitial. There were also differences in signal intensity indicating that the gene copies between and within rDNA sites might be different. The result suggests that considerable chromosome rearrangements have occurred during Boronia cyto-evolution, leading to variation among Boronia taxa in rDNA copy number, site number, and location. These changes together with dysploid reduction during cyto-evolution have made the Boronia genome considerably diverse in chromosome number, genome organization, and chromosome structure.
在九种博洛尼亚属植物的11个分类群中，对25S - 26S rDNA序列的物理位置进行了研究。在二倍体物种中，在棒状博洛尼亚（2n = 14）、羽叶博洛尼亚‘白色’（2n = 22）和纸质博洛尼亚（2n = 32）中检测到两个rDNA位点；在大柱头博洛尼亚（2n = 14）和齿叶博洛尼亚（2n = 18）中检测到四个；在羽叶博洛尼亚‘粉色’（2n = 22）中检测到六个；在莫洛亚博洛尼亚（2n = 16）中检测到八个。在异色博洛尼亚‘红色’和‘近白色’（2n = 15）中发现了11个位点，但仅观察到两个活跃的核仁组织区（NORs）。在多倍体物种中，柔毛博洛尼亚（2n = 44）有四个rDNA位点，而蓝花博洛尼亚（2n = 72）有六个。大多数rDNA序列位于末端，但有一些位于居间位置。信号强度也存在差异，这表明rDNA位点之间以及位点内部的基因拷贝可能不同。结果表明，在博洛尼亚属植物的细胞进化过程中发生了大量的染色体重排，导致博洛尼亚属分类群在rDNA拷贝数、位点数量和位置上存在差异。这些变化以及细胞进化过程中的非整倍体减少使得博洛尼亚属的基因组在染色体数目、基因组组织和染色体结构上有很大差异。
