Ephemeral flower deaths occur within 24 h of flowering in the genus Hemerocallis. The senescence of plant organs is owing to the loss of cell wall cohesion. Pectin is the most structurally complex plant cell wall polysaccharide and has an important role in cell-to-cell adhesion. In this study, we used histological stains, immunolocalization and pectin characterization analyses to examine the dynamic changes in pectin in Hemerocallis citrina ‘Datonghuanghua’ tepals at eight stages (S1–S8). The pectin-specific antibodies JIM5 and JIM7, which hybridize to differently esterified regions of the homogalacturonan (HG) backbone, showed that demethylesterification of HG-type pectins was evident after the outer tepals had opened. Before flower opening, these two antibodies labelled tissue continuously across the cell wall, and the cells were round and tightly packed. The labeling of highly esterified epitopes recognized by JIM7 became deformed when the outer tepals opened. However, 12 h after blooming, low-and high-esterified epitope signals were disrupted near the vascular cylinder, and air space then appeared until these signals disappeared. labeling with the antibody LM5, which is specific for the (1 → 4)-β galactan side chains of rhamnogalacturonan-I, was disrupted near the vascular cylinder at the same stage. Moreover, the contents of neutral sugars in pectin analyses showed that galactose decreased significantly at 12 h after blooming. Three enzymes were involved in pectin remodeling at different developmental phases. The activities of pectin methylesterase continued to increase after the outer tepals opened and reached a significant peak at 12 h after blooming. The activities of polygalacturonase and pectate lyase also increased, but the difference was not significant. Our findings revealed that demethylesterification of HG-type pectins was evident after the outer tepals opened, and this remodeling greatly facilitated their degradation by pectic enzymes. The loss of cell wall material and cohesion that accompanied the activities of pectic enzymes was associated with senescence. Therefore, remodeling of the pectin in cell walls of the tepals is necessary for the occurrence of senescence.

萱草属植物在开花后 24 小时内发生短暂的花死亡。植物器官的衰老是由于细胞壁内聚力的丧失。果胶是结构最复杂的植物细胞壁多糖，在细胞间粘附中具有重要作用。在这项研究中，我们使用组织学染色、免疫定位和果胶表征分析来检查Hemerocallis citrina中果胶的动态变化“大同黄花”花被片分八个阶段（S1-S8）。果胶特异性抗体 JIM5 和 JIM7 与同型半乳糖醛酸 (HG) 骨架的不同酯化区域杂交，表明外花被片打开后，HG 型果胶的去甲基酯化很明显。开花前，这两种抗体连续标记组织跨越细胞壁，细胞呈圆形且紧密排列。当外部花被打开时，JIM7 识别的高度酯化表位的标记发生变形。然而，开花后 12 小时，血管圆柱体附近的低和高酯化表位信号被破坏，然后出现空气空间，直到这些信号消失。用抗体 LM5 标记，该抗体对鼠李糖半乳糖醛酸-I 的 (1 → 4)-β 半乳聚糖侧链具有特异性，在同一阶段在血管圆柱附近被破坏。此外，果胶分析中中性糖的含量表明，半乳糖在开花后 12 小时显着下降。三种酶参与了不同发育阶段的果胶重塑。外花被片打开后果胶甲酯酶活性继续增加，并在开花后12小时达到显着峰值。多聚半乳糖醛酸酶和果胶酸裂解酶的活性也有所增加，但差异不显着。我们的研究结果表明，在外部花被片打开后，HG 型果胶的去甲基酯化很明显，这种重塑极大地促进了果胶酶的降解。伴随果胶酶活性的细胞壁材料和内聚力的丧失与衰老有关。所以，