Evolutionary pattern of rDNA following polyploidy in Leymus (Triticeae: Poaceae)
Evolutionary pattern of rDNA following polyploidy in Leymus (Triticeae: Poaceae)
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赖草（小麦科：禾本科）多倍体后 rDNA 的进化模式
DOI：
10.1016/j.ympev.2014.04.016
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发表时间：
2014-08-01
影响因子：
4.1
通讯作者：
Zhou, Yong-Hong
中科院分区：
文献类型：
--
作者：
Fan, Xing;Liu, Jing;Zhou, Yong-Hong
通过对多倍体赖草属（Leymus）的核糖体ITS多态性及其祖先基因组起源的研究，推测异源多倍体物种形成后rDNA基因的进化结果，并阐明ITS变异的地理格局。结果表明，不同的多倍体经历了不同的命运，包括不同阵列的维持或同质化，嵌合重复序列的出现和潜在的假基因。结果表明：（1）羊草属植物的Ns、P/F和St基因组类型分别起源于新麦草属（Psathyrostachys）、偃麦草属（AgropyMEremopyrum）和假鹅观草属（Pseudoroegneria），（2）具有优势单亲rDNA类型的赖草属物种比例较高，这可能与节段异源多倍体起源、异源倍体的核仁优势和赖草属植物的快速辐射有关;（3）异源多倍体保持多个亲本ITS类型可能与营养繁殖、核糖体位点数目和染色体定位以及轮回杂交等因素有关：（4）赖草属植物rDNA的遗传结构可能与地理起源有关;（5）中亚、北美和北欧赖草属物种的ITS序列分支可能是祖先ITS同源化的结果。我们的研究结果揭示了新的理解rDNA的进化结果异源多倍体物种形成和地理隔离。(C)2014爱思唯尔公司All rights reserved.
Ribosomal ITS polymorphism and its ancestral genome origin of polyploid Leymus were examined to infer the evolutionary outcome of rDNA gene following allopolyploid speciation and to elucidate the geographic pattern of ITS variation. The results demonstrated that different polyploids have experienced varying fates, including maintenance or homogenization of divergent arrays, occurrence of chimeric repeats and potential pseudogenes. Our data suggested that (I) the Ns, P/F, and St genomic types in Leymus were originated from Psathyrostachys, AgropyroMEremopyrum, and Pseudoroegneria, respectively; (2) the occurrence of a higher proportion of Leymus species with predominant uniparental rDNA type might associate with the segmental allopolyploid origin, nucleolar dominance of alloploids, and rapid radiation of Leymus; (3) maintenance of multiple parental ITS types in allopolyploid might result from long generation times associated to vegetative multiplication, number and chromosomal location of ribosomal loci and/or recurrent hybridization; (4) the rDNA genealogical structure of Leymus species might associate with the geographic origins; and (5) ITS sequence clade shared by Leymus species from Central Asia, North America, and Nordic might be an outcome of ancestral ITS homogenization. Our results shed new light on understanding evolutionary outcomes of rDNA following allopolyploid speciation and geographic isolation. (C) 2014 Elsevier Inc. All rights reserved.