Section of Botany, Department of Biology, National and Kapodistrian University of Athens, Athens, Greece.
Protoplasma. 2020 Jan;257(1):141-156. doi: 10.1007/s00709-019-01425-8. Epub 2019 Aug 30.
This article deals with the distribution of callose and of the homogalacturonan (HG) epitopes recognized by LM20, JIM5, and 2F4 antibodies in cell walls of differentiating and functioning stomatal complexes of the monocotyledon Zea mays and the dicotyledon Vigna sinensis. The findings revealed that, during stomatal development, in these plant species, callose appears in an accurately spatially and timely controlled manner in cell walls of the guard cells (GCs). In functioning stomata of both plants, callose constitutes a dominant cell wall matrix material of the polar ventral cell wall ends and of the local GC cell wall thickenings. In Zea mays, the LM20, JIM5, or 2F4 antibody-recognized HG epitopes were mainly located in the expanding cell wall regions of the stomatal complexes, while in Vigna sinensis, they were deposited in the local cell wall thickenings of the GCs as well as at the ledges of the stomatal pore. Consideration of the presented data favors the view that in the stomatal complexes of the monocotyledon Z. mays and the dicotyledon V. sinensis, the esterified HGs contribute to the cell wall expansion taking place during GC morphogenesis and the opening of the stomatal pore. Besides, callose and the highly de-esterified HGs allow to GC cell wall regions to withstand the mechanical stresses exerted during stomatal function.
本文探讨了在单子叶植物玉米和双子叶植物豇豆分化和功能的气孔复合体细胞壁中，胼胝质和同源半乳糖醛酸聚糖（HG）表位的分布情况，这些表位分别被 LM20、JIM5 和 2F4 抗体所识别。研究结果表明，在这些植物物种的气孔发育过程中，胼胝质以准确的时空控制方式出现在保卫细胞的细胞壁中。在这两种植物的功能气孔中，胼胝质构成了极性腹侧细胞壁末端和局部 GC 细胞壁加厚的主要细胞壁基质物质。在玉米中，LM20、JIM5 或 2F4 抗体识别的 HG 表位主要位于气孔复合体的扩展细胞壁区域，而在豇豆中，它们则沉积在 GC 的局部细胞壁加厚处以及气孔孔缘。考虑到所呈现的数据，支持以下观点，即在单子叶植物玉米和双子叶植物豇豆的气孔复合体中，酯化 HG 有助于 GC 形态发生和气孔开放过程中的细胞壁扩张。此外，胼胝质和高度去酯化 HG 允许 GC 细胞壁区域承受气孔功能过程中施加的机械应力。
