Ecologie, Systématique, Evolution, CNRS-UMR 8079, Université Paris Sud, Bât.360, 91450 Orsay, Cedex, France.
Plant Sci. 2006 Sep;171(3):424-33. doi: 10.1016/j.plantsci.2006.05.007. Epub 2006 Jun 5.
The distribution and organization of 5S and 18S-5.8S-26S (18S) rDNA were studied in 10 varieties of hexaploid Ipomoea batatas, five accessions of tetraploid Ipomeoa trifida, and six related species (five diploids, I. trifida, I. triloba, I. tiliacea, I. leucantha and I. setosa and one tetraploid, I. tabascana), by using fluorescence in situ hybridization (FISH). The FISH data obtained indicated that polyploidization was followed by decrease in the number of 18S rDNA loci in higher ploidy level and provided evidence for major genomic rearrangements and/or diploidization in polyploid I. batatas. Among the five diploid species examined, I. trifida appeared to be the most closely related to I. batatas. By contrast, I. leucantha was closed to I. tiliacea, but both species were distant from sweet potato. I. triloba and I. setosa were distantly related to the rest of Ipomoea batatas complex. The close relationship between I. trifida and I. batatas was also demonstrated by the presence of one 18S and CMA marker in these two chromosome complements only. Based on chromosome morphology, tetraploid I. trifida appeared to be more closely related to sweet potato than I. tabascana. Taking all data obtained in this study, I. trifida might be the progenitor of I. batatas, and I. tabascana, interspecific hybrid between these two species.
利用荧光原位杂交（FISH）技术，研究了 10 个四倍体番薯品种、5 个四倍体蕹菜品种和 6 个相关物种（5 个二倍体，蕹菜、三叶蕹菜、蕹菜、白柄蕹菜和五爪金龙，1 个四倍体，番薯）中 5S 和 18S-5.8S-26S（18S）rDNA 的分布和组织。FISH 数据表明，多倍化后，较高倍性水平的 18S rDNA 基因座数量减少，并为多倍体番薯中的主要基因组重排和/或二倍体化提供了证据。在所研究的 5 个二倍体物种中，蕹菜似乎与番薯最为密切相关。相比之下，白柄蕹菜与蕹菜亲缘关系较近，但与番薯相距较远。三叶蕹菜和五爪金龙与番薯复合体的其余部分亲缘关系较远。蕹菜和番薯仅在这两个染色体组中存在一个 18S 和 CMA 标记，这也证明了蕹菜和番薯之间的密切关系。根据染色体形态，四倍体蕹菜似乎与番薯的亲缘关系比番薯与番薯的亲缘关系更为密切。综合本研究的所有数据，蕹菜可能是番薯的祖先，而番薯是这两个物种的种间杂种。
