Maeda Naoki, Aoki Dan, Fujiyasu Syunya, Matsushita Yasuyuki, Yoshida Masato, Hiraide Hideto, Mitsuda Hayato, Tobimatsu Yuki, Fukushima Kazuhiko
Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
Institute of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, 183-8509, Japan.
Plant J. 2025 Jan;121(2):e17209. doi: 10.1111/tpj.17209. Epub 2024 Dec 14.
The distributions of monolignol glucosides (MLGs) in compression and opposite woods of Pinus thunbergii were assessed using cryo-time-of-flight secondary ion mass spectrometry to investigate their involvement in lignification. p-Glucocoumaryl alcohol (PG) was identified in the region of the differentiating xylem adjacent to the cambial zone only in compression wood, whereas coniferin (CF) was similarly localized in both compression and opposite woods. Their distribution from the phloem to the xylem was evaluated by high-performance liquid chromatography (HPLC) using serial tangential sections. Variations in storage amounts of CF and PG in the stem of P. thunbergii agreed with lignification stages of the tracheid, supporting the idea that MLGs act as a storage and transportation form of lignin precursors. The imaging of monolignol (ML)-dependent active lignification sites using fluorescence-tagged MLs supported distinct distribution patterns of MLGs for lignification in compression and opposite woods. Methylation-thioacidolysis was applied to compression and opposite wood samples to examine the structural difference between the guaiacyl (G) and p-hydroxyphenyl (H) units in lignin. Most of the H units in compression wood were detected as lignin end groups via thioacidolysis. PG was detected in opposite wood by HPLC; however, the H unit was not detected by thioacidolysis. The differences in ML and MLG distributions, enzyme activity, and resultant lignin structures between the G and H units suggest the possibility of individual mechanisms regulating the heterogeneous structures of G and H unit in lignin.
利用低温飞行时间二次离子质谱法评估了黑松压缩木和对应木中单木脂糖苷（MLGs）的分布，以研究它们在木质化过程中的作用。仅在压缩木中，在形成层区域附近的分化木质部区域鉴定出了对香豆醇葡萄糖苷（PG），而松柏苷（CF）在压缩木和对应木中均有类似的定位。使用连续切向切片通过高效液相色谱法（HPLC）评估了它们从韧皮部到木质部的分布。黑松茎中CF和PG储存量的变化与管胞的木质化阶段一致，支持了MLGs作为木质素前体的储存和运输形式的观点。使用荧光标记的单木脂（ML）对依赖ML的活性木质化位点进行成像，支持了压缩木和对应木中MLGs在木质化过程中不同的分布模式。对压缩木和对应木样品进行甲基化硫代酸解，以研究木质素中愈创木基（G）和对羟基苯基（H）单元之间的结构差异。通过硫代酸解，压缩木中的大多数H单元被检测为木质素端基。通过HPLC在对应木中检测到了PG；然而，通过硫代酸解未检测到H单元。G和H单元之间ML和MLG分布、酶活性以及所得木质素结构的差异表明，可能存在调节木质素中G和H单元异质结构的个体机制。
