Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland.
Department of Plant Anatomy and Cytology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
Plant Sci. 2019 Apr;281:9-18. doi: 10.1016/j.plantsci.2019.01.005. Epub 2019 Jan 11.
Arabinogalactan proteins as cell wall structural proteins are involved in fundamental processes during plant development and growth. The aim of this study was to evaluate AGP function in the distribution of pectin, cellulose and callose along Fragaria x ananassa pollen tube and to associate the cell wall structure with local mechanical properties. We used Yariv reagent which interacts with AGPs and allows the observation of the assembly of cell walls without AGPs performing their function. Cytochemical, immunofluorescence labelling and atomic force microscope have been used to characterize the changes in cell wall structure and stiffness. It was shown that disordering of the structure of AGP present in cell walls affects the localization of cellulose, pectins and the secretion of callose. Changes in cell wall assembly are relevant to pollen tube mechanical properties. The stiffness gradient lengthwise through the axis of the pollen tube has demonstrated a significantly higher Young's modulus of the shank region than the growth zone. It has been revealed that the apex of the pollen tube cultured in the presence of Yariv reagent is stiffer (1.68 MPa) than the corresponding region of the pollen tube grown under control conditions (0.13-0.27 MPa). AGP affects the structure of the cell wall by changing the distribution of other components and the modification of their localization, and hence it plays a significant role in the mechanical properties of the cell wall.
阿拉伯半乳聚糖蛋白作为细胞壁结构蛋白，参与植物发育和生长过程中的基本过程。本研究旨在评估 AGP 在果胶、纤维素和胼胝质沿草莓花粉管分布中的功能，并将细胞壁结构与局部力学性质联系起来。我们使用了与 AGP 相互作用的 Yariv 试剂，该试剂允许在不执行 AGP 功能的情况下观察细胞壁的组装。细胞化学、免疫荧光标记和原子力显微镜被用来描述细胞壁结构和刚度的变化。结果表明，细胞壁中存在的 AGP 结构的无序性会影响纤维素、果胶和胼胝质的定位以及胼胝质的分泌。细胞壁组装的变化与花粉管的力学性质有关。花粉管轴向上的刚度梯度显示，柄部区域的杨氏模量明显高于生长区。结果表明，在 Yariv 试剂存在下培养的花粉管的顶端比在对照条件下生长的花粉管的相应区域更硬（1.68 MPa）。AGP 通过改变其他成分的分布及其定位的改变来影响细胞壁的结构，因此在细胞壁的力学性质中起着重要的作用。
