Nectaries in ferns: their taxonomic distribution, structure, function, and sugar composition.
Nectaries in ferns: their taxonomic distribution, structure, function, and sugar composition.
复制标题
蕨类植物的蜜腺：它们的分类分布、结构、功能和糖成分。
DOI：
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
S. Jansen
中科院分区：
文献类型：
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作者：
K. Mehltreter;R. Tenhaken;S. Jansen
前提
花外蜜腺的研究主要集中在被子植物中，但也有39种蕨类植物的花外蜜腺。在这里，我们提供了一个全球性的审查蜜腺在蕨类植物，并研究其结构，功能和花蜜糖组成的两个属。
方法
通过文献检索和植物园植物标本收集，对紫胶蕨属（Aglaomorpha）和弯脉蕨属（Campyloneurum）2种蕨类植物的蜜腺进行形态解剖学研究，并对16种蕨类植物的总糖含量和比例进行分析。用延时摄影法观察花蜜的昼夜释放。
结果
在6科11属101种蕨类植物中发现蜜腺的证据。结果表明，蜜源植物以树蕨（桫椤科）和水龙骨科附生蕨类植物为主。蜜腺由富含细胞质的薄壁组织组成，细胞核大，表皮有气孔或无气孔，附着在两性维管束上，夜间主要在展开的叶片上在叶下表面释放花蜜。糖浓度在种间变化（3.8-15.3%），但在属间不变化，并且蔗糖占优势（3种），富含蔗糖（7）或富含己糖（3）。在温室条件下，引进的蚂蚁，介壳虫和蜗牛以花蜜为食。
结论
广泛的分类分布，多变的形态，位置和糖组成点蕨类蜜腺的多个进化起源。只有在这一最脆弱的发育阶段，嫩叶中的花蜜释放才可能吸引互利共生的蚂蚁来保护叶子免受食草动物的侵害。即使在异地，蕨类植物的花蜜也是一种有价值的食物来源，因为它吸引了几种机会主义的动物物种。本文受版权保护。All rights reserved.
PREMISE
Extrafloral nectaries are mainly studied in angiosperms, but have also been reported in 39 fern species. Here we provide a global review of nectaries in ferns, and study their structure, function, and nectar sugar composition in two genera.
METHODS
We searched in the literature and living plant collections of botanical gardens for indications of fern nectaries, studied the morpho-anatomy in the two genera Aglaomorpha and Campyloneurum, and analyzed the total sugar concentrations and ratios of 16 species. Diurnal nectar release was observed with time-lapse photography.
RESULTS
We found evidence for nectaries in 101 species of ferns from 11 genera and 6 families. Most of the nectary-bearing species were tree ferns (Cyatheaceae) and epiphytic ferns of the family Polypodiaceae. Nectaries consisted of cytoplasm-rich parenchyma with large nuclei and an epidermis with or without stomata, were attached to amphiphloic vascular bundles, and released nectar on the lower leaf surface mainly on expanding leaves during the night. Sugar concentrations varied between species (3.8-15.3%) but not between genera, and were sucrose-dominant (3 spp.), sucrose-rich (7), or hexose-rich (3). Under greenhouse conditions, introduced ants, scale insects, and snails fed on the nectar.
CONCLUSIONS
The wide taxonomic distribution, variable morphology, locations, and sugar compositions point to multiple evolutionary origins of fern nectaries. Nectar release in young leaves might attract mutualistic ants to protect leaves against herbivores only during this most vulnerable developmental stage. Even ex-situ, fern nectar is a valuable food source because it attracted several opportunistic animal species. This article is protected by copyright. All rights reserved.