镍超积累进化谱系和欧洲岩荠族（十字花科）的系统发育：来自 nrDNA 序列数据的证据。
Evolutionary lineages of nickel hyperaccumulation and systematics in European Alysseae (Brassicaceae): evidence from nrDNA sequence data.
机构信息
Department of Evolutionary Biology, University of Firenze, Via G. La Pira 4, I-50121 Firenze, Italy.
出版信息
Ann Bot. 2010 Nov;106(5):751-67. doi: 10.1093/aob/mcq162. Epub 2010 Aug 19.
BACKGROUND AND AIMS
Nickel (Ni) hyperaccumulation is a rare form of physiological specialization shared by a small number of angiosperms growing on ultramafic soils. The evolutionary patterns of this feature among European members of tribe Alysseae (Brassicaceae) are investigated using a phylogenetic approach to assess relationships among Ni hyperaccumulators at the genus, species and below-species level.
METHODS
Internal transcribed spacer (ITS) sequences were generated for multiple accessions of Alysseae. Phylogenetic trees were obtained for the genera of the tribe and Alyssum sect. Odontarrhena. All accessions and additional herbarium material were tested for Ni hyperaccumulation with the dimethylglyoxime colorimetric method.
KEY RESULTS
Molecular data strongly support the poorly known hyperaccumulator endemic Leptoplax (Peltaria) emarginata as sister to hyperaccumulator species of Bornmuellera within Alysseae. This is contrary to current assumptions of affinity between L. emarginata and the non-hyperaccumulator Peltaria in Thlaspideae. The lineage Bornmuellera-Leptoplax is, in turn, sister to the two non-hyperaccumulator Mediterranean endemics Ptilotrichum rupestre and P. cyclocarpum. Low ITS sequence variation was found within the monophyletic Alyssum sect. Odontarrhena and especially in A. murale sensu lato. Nickel hyperaccumulation was not monophyletic in any of three main clades retrieved, each consisting of hyperaccumulators and non-hyperaccumulators of different geographical origin.
CONCLUSIONS
Nickel hyperaccumulation in Alysseae has a double origin, but it did not evolve in Thlaspideae. In Bornmuellera-Leptoplax it represents an early synapomorphy inherited from an ancestor shared with the calcicolous, sister clade of Mediterranean Ptilotrichum. In Alyssum sect. Odontarrhena it has multiple origins even within the three European clades recognized. Lack of geographical cohesion suggests that accumulation ability has been lost or gained over the different serpentine areas of south Europe through independent events of microevolutionary adaptation and selection. Genetic continuity and strong phenotypic plasticity in the A. murale complex call for a reduction of the number of Ni hyperaccumulator taxa formally recognized.
背景与目的
镍（Ni）超积累是少数生长在超基性土壤上的被子植物的一种罕见的生理特化形式。本研究采用系统发育方法研究了欧洲 Alyssae 族（十字花科）成员中这一特征的进化模式，以评估属、种和种以下水平上 Ni 超积累的关系。
方法
对 Alyssae 族的多个种进行了内转录间隔区（ITS）序列的生成。获得了族中属和 Alyssum 节 Odontarrhena 的系统发育树。用二甲基甘氨酸比色法对所有种和附加标本进行 Ni 超积累测试。
结果
分子数据强烈支持，知之甚少的超积累特有种 Leptoplax（Peltaria）emarginata 与 Alyssae 中的 Bornmuellera 超积累种密切相关。这与目前 L. emarginata 与 Thlaspideae 中的非超积累种 Peltaria 之间的亲缘关系假设相反。Bornmuellera-Leptoplax 是两个非超积累地中海特有种 Ptilotrichum rupestre 和 P. cyclocarpum 的姊妹群。在单系的 Alyssum 节 Odontarrhena 中，尤其是在广义的 A. murale 中，发现 ITS 序列的低变异。在三个主要分支中，Ni 超积累都不是单系的，每个分支都由不同地理起源的超积累和非超积累组成。
结论
Alyssaeae 中的 Ni 超积累有两个起源，但它没有在 Thlaspideae 中进化。在 Bornmuellera-Leptoplax 中，它代表了一个从与地中海 calcicolous 姊妹群共享的祖先继承而来的早期的 synapomorphy。在 Alyssum 节 Odontarrhena 中，即使在识别的三个欧洲分支中，它也有多个起源。缺乏地理凝聚力表明，通过独立的微进化适应和选择事件，积累能力在南欧不同的蛇纹石地区已经丢失或获得。A. murale 复合体中的遗传连续性和强烈的表型可塑性要求减少正式承认的 Ni 超积累分类群的数量。
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