Three‐genome mosses: complex double allopolyploid origins for triploid gametophytes in Sphagnum
Three‐genome mosses: complex double allopolyploid origins for triploid gametophytes in Sphagnum
复制标题
三基因组苔藓：泥炭藓中三倍体配子体的复杂双异源多倍体起源
作者：
E. F. Karlin;S. Boles;M. Ricca;M. Ricca;E. Temsch;J. Greilhuber;A. Shaw
本文报道了南半球两种泥炭藓(S.australe，S.Falcatulum)配子体中发生异源三倍体(具有三个分化的基因组)。微卫星等位基因分析表明，这两个物种均由异源二倍体和异源三倍体配子体组成，后者是由两次异源多倍化事件产生的。两种植物均未发现单倍体(n=x)配子体。用流式细胞仪和Feulgen DNA图像密度术证实了微卫星等位基因模式所显示的倍性水平。对于南方红豆杉和南方红豆杉，各自的异源二倍体植物(或其祖先)都是异源三倍体植物的亲本物种之一。这是自然界中发现的泥炭藓配子体三倍体的首次报道，也是首次报道苔藓植物中存在三个分化的基因组。这也是首次报道Sphagnum的组间异源多倍体，南方Sphagnum的亲本种似乎来自Sphagnum组rigida和Sphagnum，而S.forcatulum的亲本种似乎来自Sphagnum组cupidata和Subsecunda。在这两个物种中，异源三倍体细胞型是新西兰南岛最常见的细胞型。微卫星等位基因的模式表明，异源二倍体南美乳杆菌存在两个遗传上截然不同的群体，这可能表明该异源二倍体细胞类型的多倍体起源。形态证据也高度表明，在异源三倍体细胞型的镰刀菌中出现了反复的多倍体。异源多倍体显然在这两个南半球分类群中发挥了重要的进化作用。这项研究结合最近的其他研究表明，异源多倍体即使不是泥炭藻属的主要多倍体形式，也是一种常见的多倍体形式。
This paper documents the occurrence of allotriploidy (having three differentiated genomes) in gametophytes of two Southern Hemisphere Sphagnum species (S. australe, S. falcatulum). The pattern of microsatellite alleles indicates that both species are composed of a complex of allodiploid and allotriploid gametophytes, with the latter resulting from two allopolyploidization events. No haploid (n = x) gametophytes were found for either species. The ploidal levels suggested by the pattern of microsatellite alleles were confirmed by flow cytometry and Feulgen DNA image densitometry. For both S. australe and S. falcatulum, the respective allodiploid plants (or their ancestors) are one of the parent species of the allotriploid plants. This is the first report of triploidy in Sphagnum gametophytes occurring in nature and also the first report of the presence of three differentiated genomes in any bryophyte. It is also the first report of intersectional allopolyploidy in Sphagnum, with S. australe appearing to have parental species from Sphagnum sections Rigida and Sphagnum, and S. falcatulum having parental species from Sphagnum sections Cuspidata and Subsecunda. In both species, the allotriploid cytotypes were the most prevalent cytotype on the South Island of New Zealand. The pattern of microsatellite alleles shows the presence of two genetically distinct populations of allodiploid S. australe, possibly indicating multiple origins of polyploidy for that allodiploid cytotype. Morphological evidence is also highly indicative of recurrent polyploidy in the allotriploid cytotype of S. falcatulum. Allopolyploidy has clearly played a major evolutionary role in these two Southern Hemisphere taxa. This study, in conjunction with other recent research, indicates that allopolyploidy is a common, if not the predominant, form of polyploidy in Sphagnum.
影响因子：
3.3
作者：
L. Excoffier;P. Smouse;J. Quattro
通讯作者：
L. Excoffier;P. Smouse;J. Quattro