Hamon P, Siljak-Yakovlev S, Srisuwan S, Robin O, Poncet V, Hamon S, de Kochko A
IRD, UMR DIAPC, 911 Av Agropolis, BP 64501, 34394, Montpellier cedex 5, France.
Chromosome Res. 2009;17(3):291-304. doi: 10.1007/s10577-009-9033-2. Epub 2009 Mar 31.
The chromosome organization among 15 wild diploid Coffea species and cultivated tetraploid C. arabica was determined by fluorochrome banding (CMA, DAPI) and double fluorescence in-situ hybridization (FISH) of 5S and 18S rDNA achieved on the same chromosome plates. Two to five chromosome pairs (plus one putative chromosome B) are marked. Overall, there are two SAT-chromosome pairs for East African species and one for the Malagasy and the West and Central African species. 18S rDNA loci are telomeric and strongly marked the SAT-chromosome pairs. Generally, only one pericentromeric 5S rDNA locus characterized East African species, while an additional minor locus co-localized with the 18S rDNA-SAT locus for the Malagasy species and West and Central African species. A combination of rDNA FISH plus CMA and DAPI banding patterns enables identification of almost all the species, even those for which the genetic or botanical status is still being discussed. C. arabica clearly appears to be an allotetraploid species, including one genome from East Africa and one from West and Central Africa. However, since the minor 5S rDNA-SAT locus present in West/Central African genomes is not detected, two evolutionary hypotheses could be put forward for C. arabica. Considering only the diploid species, global trends are obvious in rDNA signal patterns, genome size variations, and geographic distribution of the species, but there are no clear evolutionary trends. However, complex interactions between these factors and environmental growing conditions exist, which have resulted in loss and gain of rDNA loci and probably also in copy repeat number variations in each rDNA family.
通过荧光带型分析（CMA、DAPI）以及在同一染色体玻片上进行的5S和18S rDNA双重荧光原位杂交（FISH），确定了15种野生二倍体咖啡属物种和栽培四倍体阿拉伯咖啡的染色体组织。标记出了2至5对染色体（外加一条假定的B染色体）。总体而言，东非物种有两对随体染色体，马达加斯加以及西非和中非物种有一对随体染色体。18S rDNA位点位于端粒，且强烈标记了随体染色体对。一般来说，东非物种只有一个着丝粒周围的5S rDNA位点，而马达加斯加物种以及西非和中非物种还有一个与18S rDNA - 随体位点共定位的次要位点。rDNA FISH加上CMA和DAPI带型模式的组合能够鉴定几乎所有物种，甚至包括那些遗传或植物学地位仍在讨论中的物种。阿拉伯咖啡显然是一个异源四倍体物种，包括一个来自东非的基因组和一个来自西非和中非的基因组。然而，由于未检测到西非/中非基因组中存在的次要5S rDNA - 随体位点，因此可以为阿拉伯咖啡提出两种进化假说。仅考虑二倍体物种，rDNA信号模式、基因组大小变化以及物种的地理分布存在明显的全球趋势，但没有明确的进化趋势。然而，这些因素与环境生长条件之间存在复杂的相互作用，这导致了rDNA位点的丢失和增加，并且可能也导致了每个rDNA家族中拷贝重复数的变化。
