Department of Botany, The Maharaja Sayajirao of Baroda, Vadodara, 390002, Gujarat, India.
Department of Botany, The Maharaja Sayajirao of Baroda, Vadodara, 390002, Gujarat, India.
Plant Physiol Biochem. 2019 Sep;142:217-223. doi: 10.1016/j.plaphy.2019.07.013. Epub 2019 Jul 9.
Cell wall architecture of tension wood fibres represents a suitable biological system to study the mechanism of growth and maintenance of posture of trees growing under various physical and physiological growth constraints. In the present study, we investigated the spatial distributions of β-(1-4)-D-galactan, xyloglucan and xylans (both less and highly substituted) in the opposite and tension wood fibres of bent Leucaena leucocephala by immunolabelling with monoclonal antibodies LM5, CCRCM1, LM10 and LM11 specific to these carbohydrate epitopes. The presence of non-lignified, tertiary wall layer is the typical tension wood characteristic associated with the reaction xylem fibres in Leucaena. LM5 labelling of opposite fibres showed weak labelling in the cell walls indicating less concentration of β-(1-4)-D-galactans while tension wood showed strong labelling in the tertiary wall layer suggesting the gelatinous layer (G-layer) has a strong cross linking with β-(1-4)-D-galactans. Xyloglucan distribution was more in the compound middle lamellae and the primary wall-S1 layer boundary of tension wood fibres as compared to that of opposite wood. A weak labelling was also evident near the boundary between the G-layer and the secondary wall of tension wood fibres. The secondary wall of opposite and tension wood fibres showed a strong distribution of both ls ACG Xs (LM10) and hs ACG Xs (LM11) while a weak labelling was noticed in the compound middle lamella. Tension wood fibres also showed strong xylan labelling mainly confined to the lignified secondary walls while the G-layer showed weak xylan labelling. In conclusion, our results suggest that β-(1-4)-D-galactans and xyloglucans could be implicated in the tensile stress generation within the G-layer of tension wood fibres of Leucaena leucocephala.
细胞壁结构的张力木材纤维代表了一个合适的生物系统来研究生长的机制和维持的姿势的树木生长在各种物理和生理生长的限制。在本研究中，我们调查了β-(1-4)-D-半乳糖、木葡聚糖和木聚糖（低取代和高取代）在弯曲银荆的正反交纤维中的空间分布，用特异性的单克隆抗体 lm5、ccrcm1、lm10 和 lm11 进行免疫标记这些糖基表位。非木质化的第三层细胞壁是银荆反应木纤维的典型张力木特征。对反交纤维的 lm5 标记显示细胞壁的标记较弱，表明β-(1-4)-D-半乳糖的浓度较低，而张力木在第三层细胞壁上显示出强烈的标记，表明胶状层（G 层）与β-(1-4)-D-半乳糖有很强的交联。木葡聚糖的分布在张力木纤维的复合中层和初生壁-S1 层边界较多，而在反交木纤维中较少。在张力木纤维的 G 层和次生壁之间的边界附近也有明显的弱标记。正反交木纤维的次生壁均表现出较强的 lsACGXs（lm10）和 hsACGXs（lm11）分布，而在复合中层有较弱的标记。张力木纤维也表现出较强的木聚糖标记，主要局限于木质化的次生壁，而 G 层显示出较弱的木聚糖标记。总之，我们的结果表明，β-(1-4)-D-半乳糖和木葡聚糖可能与银荆的张力木纤维的 G 层中的拉伸应力产生有关。
