Hymenasplenium volubile: documentation of its gametophytes and the first record of a hemiepiphyte in the Aspleniaceae
Hymenasplenium volubile: documentation of its gametophytes and the first record of a hemiepiphyte in the Aspleniaceae
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Hymenasplenium volubile：其配子体的记录和铁角蕨科半附生植物的首次记录
DOI：
10.1093/aob/mcz124
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发表时间：
2019
期刊：
影响因子：
4.2
通讯作者：
Watkins, James E
中科院分区：
文献类型：
--
作者：
Watts, Jacob L;Moran, Robbin C;Watkins, James E
背景与目的通过对一个个体发生系中膜厚体的配子体和孢子体的生长习性进行仔细的野外考察，我们旨在更好地了解这一尚不清楚的蕨类植物群的附生进化。卷孢子体和配子体，并将标本带回实验室进行显微镜分析。在野外，拍摄了每个个体发生阶段的孢子体，以记录该物种的生长习性。我们利用现有的系统发育对新世界膜脾菌的生长形式进行了优化。主要结果：幼芽孢体最初是完全附生的，并产生一根或两根长食根，延伸到土壤中，并在土壤中大量分枝。在植物的整个生命周期中，根系都与土壤保持接触。因此,H。卷叶属半附生植物。当配子体未成熟时，它们紧贴在树干上，但是，当它们的配子体成熟时，它们的下缘向上抬起，使小体具有架子状的外观。菌体通过与底物接触的菌体边缘产生的分枝状根状体附着在底物上。结论半附生植物是附生蕨类植物进化的关键环节，可能是连接林底和林冠的桥梁。我们的发现是第一个报道的半附生植物在天门冬科，许多附生和陆生类群的大谱系。这项工作作为一个重要的模型来理解附生的进化，特别是在这个群体和蕨类植物。我们对蕨类配子体生物学的理解大部分来自实验室研究。我们的工作代表了在野外环境中理解蕨类配子体生态学的基本贡献。
Background and AimsThrough careful field examination of the growth habit of the gametophytes and sporophytes ofHymenasplenium volubileacross an ontogenetic series, we aim to understand better the evolution of epiphytism in this poorly understood group of fernsMethodsWe made field observations ofH. volubilesporophytes and gametophytes, and brought specimens back to the lab for microscopic analysis. In the field, sporophytes at each ontogenetic stage were photographed to document the species’ growth habit. We used an existing phylogeny to optimize growth form of New WorldHymenasplenium.Key ResultsYoung sporophytes were at first fully epiphytic and produced one or two long feeding roots that extend to the soil where they branch profusely. The feeding roots remain in contact with the soil throughout the life of the plant. Thus,H. volubileis a hemiepiphyte. While immature, gametophytes are appressed to the tree trunk, but, as their gametangia mature, their lower margin lifts upward, imparting a shelf-like appearance to the thallus. The thallus attaches to the substrate by branched rhizoids produced along the margin of the thallus in contact with the substrate.ConclusionsHemiepiphytes are a key link in the evolution of epiphytic ferns and may act as a bridge between the forest floor and the canopy. Our finding is the first report of hemiepiphytism in Aspleniaceae, a large lineage with many epiphytic and terrestrial taxa. This work serves as an important model to understand the evolution of epiphytism in this group specifically and in ferns in general. The majority of our understanding of fern gametophyte biology is derived from laboratory studies. Our efforts represent a fundamental contribution to understanding fern gametophyte ecology in a field setting.