Natali L, Ceccarelli M, Giordani T, Sarri V, Zuccolo A, Jurman I, Morgante M, Cavallini A, Cionini P G
Dipartimento di Biologia delle Piante Agrarie, Sezione di Genetica, Universita di Pisa, Via del Borghetto 80, 56124 Pisa, Italy.
Genome. 2008 Dec;51(12):1047-53. doi: 10.1139/G08-089.
The amplification and chromosomal localization of tandem repeated DNA sequences from Helianthus annuus (clone HAG004N15) and the physical organization of ribosomal DNA were studied in annual and perennial species of Helianthus. HAG004N15-related sequences, which did not show amplification in other Asteraceae except for Viguiera multiflora, were redundant in all the Helianthus species tested, but their frequency was significantly higher in perennials than in annuals. These sequences were located at the ends and intercalary regions of all chromosome pairs of annual species. A similar pattern was found in the perennials, but a metacentric pair in their complement was not labelled. Ribosomal cistrons were carried on two chromosome pairs in perennials and on three pairs in annuals except for H. annuus, where rDNA loci were on four pairs. No difference was observed between cultivated H. annuus and its wild accessions in the hybridization pattern of the HAG004N15 and ribosomal probes. These findings support the hypothesis that the separation between annual and perennial Helianthus species occurred through interspecific hybridization involving at least one different parent. However, GISH in H. annuus using genomic DNA from the perennial Helianthus giganteus as blocking DNA failed to reveal different genomic assets in annual and perennial species.
对向日葵属一年生和多年生物种中来自向日葵（克隆HAG004N15）的串联重复DNA序列的扩增和染色体定位以及核糖体DNA的物理组织进行了研究。除了多花假向日葵外，在其他菊科植物中未显示扩增的HAG004N15相关序列，在所有测试的向日葵物种中都是多余的，但它们在多年生植物中的频率明显高于一年生植物。这些序列位于一年生物种所有染色体对的末端和居间区域。在多年生植物中也发现了类似的模式，但它们染色体组中的一对中着丝粒染色体未被标记。多年生植物的核糖体顺反子分布在两对染色体上，一年生植物（除向日葵外）分布在三对染色体上，而向日葵的核糖体DNA位点分布在四对染色体上。在HAG004N15和核糖体探针的杂交模式中，栽培向日葵与其野生近缘种之间未观察到差异。这些发现支持了这样一种假设，即一年生和多年生向日葵物种之间的分离是通过涉及至少一个不同亲本的种间杂交发生的。然而，以多年生巨型向日葵的基因组DNA作为封闭DNA对向日葵进行基因组原位杂交，未能揭示一年生和多年生物种中不同的基因组特征。
