Ann Mo Bot Gard:中科院昆明植物所王红研究组发表被子植物单子叶分

近日，国际植物学期刊 《Annals of the Missouri Botanical Garden》在线发表中科院昆明植物所王红研究组与英国爱丁堡皇家植物园 Stephen Blackmore 教授合作发表题为“evolution of Angiosperm Pollen. 3. Monocots”的研究成果。该项目通过大尺度、大规模的取样，利用多种分析方法，系统开展被子植物花粉形态演化式样的研究，以厘清被子植物花粉的起源和演化问题，并探讨主要的驱动因子。博士生骆洋和陆露副研究员为该论文的并列第一作者。

花粉形态学作为广义形态学的一个分支，可以作为建立高级分类阶元的一个重要依据。随着大量的花粉形态数据的不断累积，以及分子系统学研究的快速发展，使得利用花粉形态性状重新审视被子植物各大分支及其以下阶元的系统演化关系成为可能。

王红研究员带领的研究团队，基于单子叶分支(Monocots)目前最完善的分子系统框架，对该分支12目70个科125属的19个花粉形态性状进行了整合分析。研究发现：单子叶花粉形态多样，泽泻目(Alismatales)和鸭跖草目(Commelinales)的花粉性状在所研究类群中转变频次较高，天门冬目(Asparagales)、多须草目(Dasypogonales)和姜目(Zingiberales)则较低;花粉极面观(Outline in polar view)、花粉大小(Size)和覆盖层(Tectum)在演化过程中转变较频繁。花粉形态性状具重要分类意义，如在泽泻目3个主要分支：岩菖蒲科 TofieldiAceae、天南星科 Araceae 和泽泻分支 alismatids 中;明晰了对一些具争议的系统位置，如鸭跖草分支 commelinids 内部五个目，以及禾本目 Poales 的基部类群的系统关系。同时，研究揭示了在白垩纪的阿尔布阶到土伦阶期间(Albian-Turonian Stage)发生了剧烈的花粉形态演变，可能与该时期的环境气候相关。削减的外壁、覆盖层、中间层和柱状层的丢失与潮湿或沼生-水生环境高度相关。覆盖层的变化响应了生境湿度的转变，柱状层在水生环境中丢失。

原文链接：

evolution of Angiosperm Pollen. 3. Monocots

原文摘要：

Monocots, with ca. 65,000 species in 78 families and 12 orders as classified by the Angiosperm Phylogeny Group (Angiosperm Phylogeny Group III, 2009), have traditionally been known as a distinct assemblage from dicots within angiosperms and are now seen as a lineage that diverged from within the more basal of the angiosperm groupings. In this study, the third in a series analyzing pollen characters across the angiosperms, we illustrate the pollen morphological diversity of monocots and analyze 19 palynological and two ecological characters for 120 taxa in 71 families covering the 12 monocot orders and 16 taxa of nine orders in basal angiosperms. Pollen morphological data from previous works and our investigations were optimized onto a new maximum likelihood tree reconstructed from an existing DNA matrix of Chase et al. (2006) using Fitch parsimony, maximum likelihood, and hierarchical Bayesian analysis. From these analyses we infer evolutionary patterns in palynological characters, assess their systematic value, and investigate two aspects (pollination type and habitat moisture) of their ecological adaptation. The highest levels of pollen variation were shown to exist in the Alismatales and Commelinales, with lower levels seen in the Asparagales, Dasypogonales, and Zingiberales; the most variable characters across the phylogeny were found to be pollen outline in polar view, size, and tectum extent. We infer unambiguous plesiomorphic states for monocots and report significant transitions in character states at various levels within the monocot assemblage. Analyses of correlated evolution reconfirmed the hypothesis of an association between exine reduction (or complete loss) and habitat moisture and found significant correlations between various states of exine loss and habitat for hydrophytic–helophytic plants. The presence or absence of the exine itself was found to be more significantly correlated than individual structures, in terms of association with hydrophytic–helophytic plants. The most rapid rate of state changes in pollen characters, in the evolutionary history of monocots, is estimated to have occurred during the Albian-Turonian stage; our work may provide insights into the identification of enigmatic fossil pollen grains from this geological time.

doi: http://dx.doi.org/10.3417/2014014

作者：王红