Chemical composition of cell walls in velamentous roots of epiphytic Orchidaceae
Chemical composition of cell walls in velamentous roots of epiphytic Orchidaceae
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DOI：
10.1007/s00709-019-01421-y
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发表时间：
2020-01-01
期刊：
影响因子：
2.9
通讯作者：
Moreira, Ana Silvia Franco Pinheiro
中科院分区：
文献类型：
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作者：
Joca, Thais Arruda Costa;de Oliveira, Denis Coelho;Moreira, Ana Silvia Franco Pinheiro
细胞壁的化学成分强烈影响根组织的透水性和贮水量。由于附生兰花生活在一个栖息地与高度波动的供水，根细胞壁是功能重要。在本研究中，我们使用组织化学和免疫细胞化学技术，以确定18个附生物种的根组织的细胞壁的组成，属于7个亚族在兰科。木质素在被膜细胞中的浸渍加强了其作为机械支持的功能，并可以促进质外体流动。果胶以及纤维素和木质素对于膜细胞的稳定性和机械支持也是必不可少的。外皮层和内皮层具有木栓化的薄层和通常的木质化壁，其作为选择性屏障对质外体流动起作用。各种皮层薄壁次生壁增厚，包括φ，网状，和均匀，防止皮层在干燥期间崩溃。皮层薄壁组织中高度甲基化的果胶的存在促进了凝胶的形成，导致壁松弛和孔隙度增加，这有助于细胞之间的水储存和溶质运输。最后，皮层薄壁组织中含有脂质或木质素的细胞可以增加向中柱的水流。
The chemical composition of the cell walls strongly affects water permeability and storage in root tissues. Since epiphytic orchids live in a habitat with a highly fluctuating water supply, the root cell walls are functionally important. In the present study, we used histochemistry and immunocytochemistry techniques in order to determine the composition of the cell walls of root tissues of 18 epiphytic species belonging to seven subtribes across the Orchidaceae. The impregnation of lignin in the velamen cells reinforces its function as mechanical support and can facilitate apoplastic flow. Pectins, as well cellulose and lignins, are also essential for the stability and mechanical support of velamen cells. The exodermis and endodermis possess a suberinized lamella and often lignified walls that function as selective barriers to apoplastic flow. Various cortical parenchyma secondary wall thickenings, including phi, reticulated, and uniform, prevent the cortex from collapsing during periods of desiccation. The presence of highly methyl-esterified pectins in the cortical parenchyma facilitates the formation of gels, causing wall loosening and increased porosity, which contributes to water storage and solute transport between cells. Finally, cells with lipid or lignin impregnation in the cortical parenchyma could increase the water flow towards the stele.