Multiple Polyploidy Events in the Early Radiation of Nodulating and Nonnodulating Legumes
Multiple Polyploidy Events in the Early Radiation of Nodulating and Nonnodulating Legumes
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DOI：
10.1093/molbev/msu296
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发表时间：
2015-01-01
影响因子：
10.7
通讯作者：
Leebens-Mack, Jim
中科院分区：
文献类型：
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作者：
Cannon, Steven B.;McKain, Michael R.;Leebens-Mack, Jim
关于庞大而多样的豆科植物家族的进化尚未解决的问题包括多倍体（全基因组重复；WGDs）相对于豆科主要谱系起源的时间以及共生固氮的起源。先前的研究已经证实，WGD影响了凤蝶科的大多数谱系，并且发生在凤蝶类和拟蝇类分支分化之后的某个时间，但确切的时间尚不清楚。除凤蝶科外，豆科谱系的WGD历史也尚未建立。通过查询来自20种不同豆科植物和17种外群物种的转录组和基因组数据构建的数千棵系统发育树，研究了WGDs在豆科植物中的存在和时间。基因树中重复的时间表明，这种突变发生在所有凤蝶的共同祖先。凤蝶科最早的分化谱系既包括结瘤分类，如属类（如罗平）、黄芪类（如花生）、相类（如豆类）和瘿类（=苜蓿，如三叶草），也包括非结瘤分类的分支，包括黄原属和枝属（在本研究中进行了评估）。我们还在其他主要豆科谱系（包括Mimosoideae-Cassiinae-Caesalpinieae， MCC）、Detarieae和Cercideae分支)的基部附近发现了几个独立的wgd的证据。结瘤存在于MCC和凤蝶枝中，两者都经历了祖先的WGDs。然而，在这两个分支中都有许多非结瘤谱系，这使得人们不清楚结瘤的系统发育分布是由于独立的增益还是由于单一起源之后的多重损失。
Unresolved questions about evolution of the large and diverse legume family include the timing of polyploidy (wholegenome duplication; WGDs) relative to the origin of themajor lineages within the Fabaceae and to the origin of symbiotic nitrogen fixation. Previous work has established that a WGD affects most lineages in the Papilionoideae and occurred sometime after the divergence of the papilionoid and mimosoid clades, but the exact timing has been unknown. The history of WGD has also not been established for legume lineages outside the Papilionoideae. We investigated the presence and timing of WGDs in the legumes by querying thousands of phylogenetic trees constructed from transcriptome and genome data from 20 diverse legumes and 17 outgroup species. The timing of duplications in the gene trees indicates that the papilionoid WGD occurred in the common ancestor of all papilionoids. The earliest diverging lineages of the Papilionoideae include both nodulating taxa, such as the genistoids (e.g., lupin), dalbergioids (e.g., peanut), phaseoloids (e.g., beans), and galegoids (= Hologalegina, e.g., clovers), and clades with nonnodulating taxa including Xanthocercis and Cladrastis (evaluated in this study). We also found evidence for several independent WGDs near the base of other major legume lineages, including the Mimosoideae-Cassiinae-Caesalpinieae (MCC), Detarieae, and Cercideae clades. Nodulation is found in the MCC and papilionoid clades, both of which experienced ancestral WGDs. However, there are numerous nonnodulating lineages in both clades, making it unclear whether the phylogenetic distribution of nodulation is due to independent gains or a single origin followed by multiple losses.