Wx intron variations support an allohexaploid origin of the sweetpotato [Ipomoea batatas (L.) Lam]
Wx intron variations support an allohexaploid origin of the sweetpotato [Ipomoea batatas (L.) Lam]
复制标题
DOI：
10.1007/s10681-010-0275-z
复制
发表时间：
2011-01-01
期刊：
影响因子：
1.9
通讯作者：
Barnes, Sandra
中科院分区：
文献类型：
--
作者：
Gao, Ming;Ashu, Glory M.;Barnes, Sandra
为了阐明甘薯的多倍体起源，我们分析了 27 个甘薯品系和 24 个选定的近缘种中三种独特类型的蜡内含子 2 (Wx-In2) 变异的保留情况，以及它们与 11 个最近亲缘关系的 Wx-In2 的系统发育关系。 Wx-In2的三种类型有效地区分了甘薯中同源性非常接近的三种二倍体组成基因组：I型是基因组I和III中的一些基因座的特征，II型和III型是基因组II和III中的基因座特有的。发现 I 型 Wx-In2 变异保留在 19 个甘薯品系中：Ipomoea littoralis Blume (4x)、I. tabascana (4x) 和 I. tenuissima (2x)； II 型将保留在所有 27 个甘薯品系、I. littoralis Blume 和两个 I. trifida 种质中； III 型保留在 13 个甘薯品系、I. tenuissima 和 4 个远缘物种中。由于直系同源内含子序列的独立随机分歧的性质，四个二倍体或四倍体甘薯近缘种之间基因组特异性或特征性甘薯Wx-In2变异的这些高度选择性保留仅与甘薯二倍体基因组的单独谱系一致。甘薯的这种异源六倍体起源可能是通过 I. tenuissima 和 I. littoralis Blume 之间的杂交发生的，后者早期源自 I. trifida 和 I. tenuissima 的一个未鉴定的同胞物种。然而，既不能排除塔巴斯卡纳的参与，也不能排除甘薯的多重起源。来自甘薯的三种类型的 Wx-In2 和来自其 11 个近亲的 Wx-In2 之间的最大似然关系支持了这一推论。
To clarify the polyploid origin of the sweetpotato, we analyzed retentions of three distinctive types of Waxy intron 2 (Wx-In2) variants among 27 sweetpotato lines and 24 selected relatives and their phylogenetic relationships with Wx-In2 from 11 closest relatives. The three types of Wx-In2 effectively distinguish three diploid constituent genomes of very close homeology in the sweetpotato: Type I is characteristic of some loci in Genome I and III, and Types II and III are specific to loci in Genome II and III. The Type I Wx-In2 variation was found to be retained in 19 sweetpotato lines, Ipomoea littoralis Blume (4x), I. tabascana (4x), and I. tenuissima (2x); Type II to be retained in all 27 sweetpotato lines, I. littoralis Blume, and two I. trifida accessions; Type III to be retained in 13 sweetpotato lines, I. tenuissima, and four distantly related species. Because of the nature of independent random divergence of orthologous intronic sequences, these highly selective retentions of genome-specific or characteristic sweetpotato Wx-In2 variations among four diploid or tetraploid sweetpotato relatives are consistent only with separate lineages of diploid genomes of the sweetpotato. Such an allohexaploid origin of the sweetpotato probably occurred via hybridization between I. tenuissima and I. littoralis Blume, derived earlier from I. trifida and an unidentified species sibling to I. tenuissima. However, neither the involvement of I. tabascana nor a multiple origin of the sweetpotato can be ruled out. The inference is supported by maximal likelihood relationships between the three types of Wx-In2 from the sweetpotato and Wx-In2 from its 11 closest relatives.