The velamen of epiphytic orchids: Variation in structure and correlations with nutrient absorption
The velamen of epiphytic orchids: Variation in structure and correlations with nutrient absorption
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DOI：
10.1016/j.flora.2017.03.009
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发表时间：
2017-05-01
期刊：
影响因子：
1.9
通讯作者：
Franco Pinheiro Moreira, Ana Silvia
中科院分区：
文献类型：
--
作者：
Costa Joca, Thais Arruda;de Oliveira, Denis Coelho;Franco Pinheiro Moreira, Ana Silvia
附生兰花的根通常具有根根，即由死细胞组成的多层表皮。根皮、皮层和维管柱的结构如何促进水和养分流向植物，很大程度上尚未被探索。到目前为止，结构根特征很少与功能属性相关。在这项研究中，我们比较了 18 个附生兰花类群的根的解剖特征和养分吸收率（特别是磷和铷）。横断面面积的相对比例从11%到97%不等。具有最大相对面积的物种有利于水和营养物质的流动，而维管柱和皮层相对比例较大的物种具有更多数量的原木质部链和内皮层传代细胞。内皮层中传代细胞的数量和皮质细胞中壁增厚的差异可能在质外体和共质体流动中发挥重要作用。带负电荷的帆膜果胶基质可以保留阳离子（如 Rb+），而木质部中有更多数量的链与内皮层的传代细胞对齐，可以促进这些离子进入维管柱。 (C) 2017 爱思唯尔有限公司。版权所有。
Roots of epiphytic orchids typically possess a velamen radicum, a multiple epidermis composed of dead cells. It is largely unexplored how the structure of the velamen, the cortex and vascular cylinder facilitate the flow of water and nutrients towards the plant. Up to now, structural root features were rarely correlated with functional attributes. In this study, we compare anatomical features with nutrient uptake rates (specifically of phosphorus and rubidium) of roots of 18 taxa of epiphytic orchids. The relative proportion of the velamen of the cross-sectional area varied from 11 to 97%. Species with the largest relative velamen area facilitate the flow of water and nutrients, and species with larger relative proportion of vascular cylinder and cortex have a greater number of protoxylem strands and passage cells of the endodermis. The number of passage cells in the endodermis and of differential wall thickenings in cortical cells may play an important role in apoplastic and symplastic flow. The velamen pectic matrix, with negative charge, can retain cations (like Rb+), while a higher number of strands in the xylem, aligned with passage cells of the endodermis, could facilitate the entry of these ions into the vascular cylinder. (C) 2017 Elsevier GmbH. All rights reserved.