轮生贯众的脊状管中富含延伸的基质，可能起到导水通道的作用。
An extensin-rich matrix lines the carinal canals in Equisetum ramosissimum, which may function as water-conducting channels.
机构信息
Pteridology, Department of Biology, Ghent University, KL Ledeganckstraat 35, B-9000 Ghent, Belgium.
出版信息
Ann Bot. 2011 Aug;108(2):307-19. doi: 10.1093/aob/mcr161. Epub 2011 Jul 12.
BACKGROUND AND AIMS
The anatomy of Equisetum stems is characterized by the occurrence of vallecular and carinal canals. Previous studies on the carinal canals in several Equisetum species suggest that they convey water from one node to another.
METHODS
Cell wall composition and ultrastructure have been studied using immunocytochemistry and electron microscopy, respectively. Serial sectioning and X-ray computed tomography were employed to examine the internode-node-internode transition of Equisetum ramosissimum.
KEY RESULTS
The distribution of the LM1 and JIM20 extensin epitopes is restricted to the lining of carinal canals. The monoclonal antibodies JIM5 and LM19 directed against homogalacturonan with a low degree of methyl esterification and the CBM3a probe recognizing crystalline cellulose also bound to this lining. The xyloglucan epitopes recognized by LM15 and CCRC-M1 were only detected in this lining after pectate lyase treatment. The carinal canals, connecting consecutive rings of nodal xylem, are formed by the disruption and dissolution of protoxylem elements during elongation of the internodes. Their inner surface appears smooth compared with that of vallecular canals.
CONCLUSIONS
The carinal canals in E. ramosissimum have a distinctive lining containing pectic homogalacturonan, cellulose, xyloglucan and extensin. These canals might function as water-conducting channels which would be especially important during the elongation of the internodes when protoxylem is disrupted and the metaxylem is not yet differentiated. How the molecularly distinct lining relates to the proposed water-conducting function of the carinal canals requires further study. Efforts to elucidate the spatial and temporal distribution of cell wall polymers in a taxonomically broad range of plants will probably provide more insight into the structural-functional relationships of individual cell wall components or of specific configurations of cell wall polymers.
背景与目的
木贼茎的解剖结构的特征是存在凹沟和脊槽。先前对几种木贼属植物的脊槽的研究表明，它们将水从一个节点输送到另一个节点。
方法
使用免疫细胞化学和电子显微镜分别研究细胞壁成分和超微结构。采用连续切片和 X 射线计算机断层扫描检查了节节木贼的节-节间-节间过渡。
主要结果
LM1 和 JIM20 伸展素表位的分布仅限于脊槽的衬里。针对低甲酯化同型半乳糖醛酸聚糖的单克隆抗体 JIM5 和 LM19 以及识别结晶纤维素的 CBM3a 探针也与该衬里结合。只有在用果胶裂解酶处理后，才会在这个衬里中检测到识别木葡聚糖表位的 LM15 和 CCRC-M1。连接连续节位木质部的脊槽是在节间伸长过程中破坏和溶解原生木质部元素形成的。与凹沟相比，它们的内表面显得光滑。
结论
节节木贼的脊槽具有独特的衬里，其中含有果胶同型半乳糖醛酸聚糖、纤维素、木葡聚糖和伸展素。这些脊槽可能作为导水通道，在节间伸长过程中，特别是在原生木质部被破坏而次生木质部尚未分化时，这些通道尤为重要。分子上不同的衬里与脊槽的拟议导水功能之间的关系需要进一步研究。阐明细胞壁聚合物在广泛的分类植物中的时空分布的努力，可能会为单个细胞壁成分的结构-功能关系或细胞壁聚合物的特定构型提供更多的深入了解。
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