Esterified phenolics occur as γ -linked lignin acylations in many plant taxa but little is known about the distribution or function of such groups. In the family Salicaceae, p -hydroxybenzoate groups are present in the lignin of poplars ( Populus spp.) and willows ( Salix spp.). In this study, the distribution of cell wall-bound p -hydroxybenzoate was examined in different tissue and cell types of poplar and willow trees. This analysis showed that p -hydroxybenzoate groups were most prevalent in juvenile stems, and were elevated in tension wood and following nitrogen fertilisation. Closer examination of stem cross-sections using time-of-flight secondary-ion mass spectrometry (ToF-SIMS) directly showed that p -hydroxybenzoate groups occur predominantly in the cell walls of fibres and are largely absent from vessel elements. These results point to a role for ester-linked groups in modifying the syringyl-rich lignin of fibres, perhaps to strengthen the cell walls of these structural elements or to increase lignification rates.

中文翻译：

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ToF-SIMS成像显示对羟基苯甲酸酯基团专门修饰了杨木和柳树木质部中纤维的木质素

酯化酚类物质在许多植物类群中以γ-连接的木质素酰化形式出现，但对这类基团的分布或功能知之甚少。在杨柳科中，对羟基苯甲酸酯基团存在于杨树（Populus spp。）和柳树（Salix spp。）的木质素中。在这项研究中，检查了细胞壁结合的对羟基苯甲酸酯在杨树和柳树的不同组织和细胞类型中的分布。该分析表明，对羟基苯甲酸酯基团在未成年人的茎中最普遍，并且在张力木材中和氮肥施肥后升高。使用飞行时间二次离子质谱（ToF-SIMS）对茎横断面进行更仔细的检查，直接表明对羟基苯甲酸酯基主要出现在纤维的细胞壁中，并且在容器元件中基本上不存在。