{"title":"The structural organization of the outer tissues in the gametophytic stem of the umbrella moss Hypnodendron menziesii optimizes load bearing.","authors":"Ramesh R Chavan, Adya P Singh","doi":"10.1007/s00425-024-04503-1","DOIUrl":null,"url":null,"abstract":"<p><strong>Main conclusion: </strong>The ultrastructural design and biochemical organization of the significantly thickened outer tissues of the gametophytic stem of Hypnodendron menziesii optimizes load bearing of the stem. Hypnodendron menziesii is a bryoid umbrella moss growing in high humid conditions on the forest floors of New Zealand. The erect gametophyte bears up to eight whorls of branches in succession, spreading across the stem that bears the heavy weight of branches with highly hydrated leaves. Our investigation using a combination of light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and TEM-immunolabeling techniques provided novel information on the structural design and biochemical organization of greatly thickened cell walls of epidermal, hypodermal, and outermost cortical tissues, comparing underlying thin-walled cortical tissues in the gametophytic stem. Probing into the ultrastructure of the cell wall architecture of these target tissues by TEM and SEM revealed the cell walls to display a multilamellar organization, in addition to demonstrating the presence of an electron-dense substance in the cell wall, presumably flavonoids. The pattern of distribution and concentration of rhamnogalacturonan, homogalacturonan, and heteromannan, as determined by immunogold labeling, suggests that it is the combination of structural and molecular design of the cell wall that may optimize the mechanical function of the epidermal, hypodermal, and outer cortical tissues. Statistical relationships between the overall thickness of epidermal, hypodermal, and outer cortical cell walls, the lumen area of cells and the percentage area of cell wall occupied in these tissues at different heights of the stem, and thickness of secondary cell wall layers (L1-L4/5) were explored. The results of these analyses unequivocally support the contribution of outer tissues to the mechanical strength of the resilient stem.</p>","PeriodicalId":20177,"journal":{"name":"Planta","volume":null,"pages":null},"PeriodicalIF":3.6000,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Planta","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1007/s00425-024-04503-1","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"PLANT SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Main conclusion: The ultrastructural design and biochemical organization of the significantly thickened outer tissues of the gametophytic stem of Hypnodendron menziesii optimizes load bearing of the stem. Hypnodendron menziesii is a bryoid umbrella moss growing in high humid conditions on the forest floors of New Zealand. The erect gametophyte bears up to eight whorls of branches in succession, spreading across the stem that bears the heavy weight of branches with highly hydrated leaves. Our investigation using a combination of light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and TEM-immunolabeling techniques provided novel information on the structural design and biochemical organization of greatly thickened cell walls of epidermal, hypodermal, and outermost cortical tissues, comparing underlying thin-walled cortical tissues in the gametophytic stem. Probing into the ultrastructure of the cell wall architecture of these target tissues by TEM and SEM revealed the cell walls to display a multilamellar organization, in addition to demonstrating the presence of an electron-dense substance in the cell wall, presumably flavonoids. The pattern of distribution and concentration of rhamnogalacturonan, homogalacturonan, and heteromannan, as determined by immunogold labeling, suggests that it is the combination of structural and molecular design of the cell wall that may optimize the mechanical function of the epidermal, hypodermal, and outer cortical tissues. Statistical relationships between the overall thickness of epidermal, hypodermal, and outer cortical cell walls, the lumen area of cells and the percentage area of cell wall occupied in these tissues at different heights of the stem, and thickness of secondary cell wall layers (L1-L4/5) were explored. The results of these analyses unequivocally support the contribution of outer tissues to the mechanical strength of the resilient stem.
主要结论男人草(Hypnodendron menziesii)配子体茎部明显增厚的外部组织的超微结构设计和生化组织优化了茎部的承重能力。Hypnodendron menziesii 是一种生长在新西兰森林地面高湿度条件下的白蜡伞苔。直立的配子体可连续生出多达八轮分枝,在茎干上蔓延,而茎干则承受着带有高水合叶片的分枝的重压。我们采用光镜、透射电子显微镜(TEM)、扫描电子显微镜(SEM)和 TEM 免疫标记技术进行了综合研究,为配子体茎中表皮、下表皮和最外层皮层组织的细胞壁大幅增厚的结构设计和生化组织提供了新的信息,并对配子体茎中薄壁皮层组织的底层进行了比较。利用 TEM 和 SEM 对这些目标组织的细胞壁结构的超微结构进行了探测,发现细胞壁呈现多层组织结构,此外还显示细胞壁中存在电子致密物质,可能是黄酮类化合物。通过免疫金标记确定的鼠李糖、同源半乳糖醛酸和杂甘露聚糖的分布和浓度模式表明,细胞壁的结构和分子设计相结合,可能会优化表皮、下表皮和外皮层组织的机械功能。研究人员探讨了表皮、下胚层和外皮层细胞壁的总体厚度、细胞腔面积和这些组织在茎的不同高度所占细胞壁面积的百分比以及次生细胞壁层(L1-L4/5)厚度之间的统计关系。这些分析结果明确支持外层组织对弹性茎机械强度的贡献。
期刊介绍:
Planta publishes timely and substantial articles on all aspects of plant biology.
We welcome original research papers on any plant species. Areas of interest include biochemistry, bioenergy, biotechnology, cell biology, development, ecological and environmental physiology, growth, metabolism, morphogenesis, molecular biology, new methods, physiology, plant-microbe interactions, structural biology, and systems biology.