Ha S, Moore P H, Heinz D, Kato S, Ohmido N, Fukui K
Department of Genetics & Pathology, Hawaii Agriculture Research Center, Aiea, 96701, USA.
Plant Mol Biol. 1999 Apr;39(6):1165-73. doi: 10.1023/a:1006133804170.
Somatic chromosomes of a wild relative of sugarcane (Saccharum spontaneum L.) anther culture-derived clone (AP 85-361, 2n = 32) were identified and characterized by computer-aided imaging technology and molecular cytological methods. The presence of four satellite chromosomes and four nearly identical chromosome sets suggests that the clone is a tetrahaploid with the basic number x = 8. A quantitative chromosome map, or idiogram, was developed using image analysis of the condensation pattern (CP) at the prometaphase stage of somatic chromosomes. The 45S and 5S ribosomal RNA gene (rDNA) loci were simultaneously visualized by multi-color fluorescence in situ hybridization (McFISH) and precisely localized to the regions of 3p3.1 and 6q1.3 on the idiogram. The simultaneous visualization of two sets of four ribosomal RNA genes confirms tetraploidy of this clone. This conclusion is consistent with results of molecular marker mapping. The quantitative chromosome map produced will become the foundation for genome analyses based on chromosome identity and structure. Previously impossible identification of small chromosomes and untestable hypotheses about the polyploid nature of plants can now be settled with these two approaches of quantitative karyotyping and FISH.
利用计算机辅助成像技术和分子细胞学方法，对甘蔗野生近缘种（甜根子草，2n = 32）花药培养衍生克隆（AP 85 - 361）的体细胞染色体进行了鉴定和特征分析。该克隆存在4条随体染色体和4个近乎相同的染色体组，表明其为基数x = 8的四倍体。通过对体细胞染色体前中期凝聚模式（CP）进行图像分析，构建了定量染色体图（核型图）。利用多色荧光原位杂交（McFISH）同时对45S和5S核糖体RNA基因（rDNA）位点进行可视化，并将其精确定位到核型图上的3p3.1和6q1.3区域。两组四个核糖体RNA基因的同时可视化证实了该克隆的四倍体性质。这一结论与分子标记作图结果一致。所产生的定量染色体图将成为基于染色体同一性和结构进行基因组分析的基础。借助这两种定量核型分析和荧光原位杂交方法，以往无法实现的小染色体鉴定以及关于植物多倍体性质的不可验证假说，如今都能够得到解决。
