Institute of Botany, University of Basel, Switzerland, Schönbeinstrasse 6, CH-4056 Basel, Switzerland.
Plant Physiol Biochem. 2010 Jan;48(1):1-8. doi: 10.1016/j.plaphy.2009.09.008. Epub 2009 Oct 9.
Hemicelluloses are the second most abundant polysaccharide in nature after cellulose. So far, the chemical heterogeneity of cell-wall hemicelluloses and the relatively large sample-volume required in existing methods represent major obstacles for large-scale, cross-species analyses of this important plant compound. Here, we apply a new micro-extraction method to analyse hemicelluloses and the ratio of 'cellulose and lignin' to hemicelluloses in different tissues of 28 plant species comprising four plant functional types (broad-leaved trees, conifers, grasses and herbs). For this study, the fiber analysis after Van Soest was modified to enable the simultaneous quantitative and qualitative measurements of hemicelluloses in small sample volumes. Total hemicellulose concentrations differed markedly among functional types and tissues with highest concentration in sapwood of broad-leaved trees (31% d.m. in Fraxinus excelsior) and lowest concentration between 10 and 15% d.m. in leaves and bark of woody species as well as in roots of herbs. As for total hemicellulose concentrations, plant functional types and tissues exhibited characteristic ratios between the sum of cellulose plus lignin and hemicelluloses, with very high ratios (>4) in bark of trees and low ratios (<2) in all investigated leaves. Additional HPLC analyses of hydrolysed hemicelluloses showed xylose to be the dominant hemicellulose monosaccharide in tissues of broad-leaved trees, grasses and herbs while coniferous species showed higher amounts of arabinose, galactose and mannose. Overall, the micro-extraction method permitted for the simultaneous determination of hemicelluloses of various tissues and plant functional types which exhibited characteristic hemicellulose concentrations and monosaccharide patterns.
半纤维素是自然界中仅次于纤维素的第二大丰富多糖。到目前为止，细胞壁半纤维素的化学异质性和现有方法所需的相对较大的样品体积是对这种重要植物化合物进行大规模跨物种分析的主要障碍。在这里，我们应用一种新的微提取方法来分析 28 种植物物种不同组织中的半纤维素和“纤维素和木质素”与半纤维素的比例，这些植物物种包括四个植物功能类型（阔叶树、针叶树、草和草本植物）。在这项研究中，对 Soest 之后的纤维分析进行了修改，以便能够在小样品体积中同时进行半纤维素的定量和定性测量。功能类型和组织之间的总半纤维素浓度差异明显，阔叶树边材中的浓度最高（欧洲白蜡木中为 31%干重），而木质物种的叶片和树皮以及草本植物的根中的浓度最低，在 10%到 15%干重之间。对于总半纤维素浓度，植物功能类型和组织表现出纤维素加木质素与半纤维素之和的特征比例，树木的树皮比例非常高（>4），而所有研究的叶片的比例则很低（<2）。对半纤维素水解产物的 HPLC 分析表明，在阔叶树、草和草本植物的组织中，木糖是主要的半纤维素单糖，而针叶树物种则含有更多的阿拉伯糖、半乳糖和甘露糖。总的来说，微提取方法允许同时确定各种组织和植物功能类型的半纤维素，这些组织和植物功能类型表现出特征性的半纤维素浓度和单糖模式。
