Structure and distribution of lignin in primary and secondary cell walls of maize coleoptiles analyzed by chemical and immunological probes
Structure and distribution of lignin in primary and secondary cell walls of maize coleoptiles analyzed by chemical and immunological probes
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DOI：
10.1007/bf01007699
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发表时间：
1997-02-01
期刊：
影响因子：
4.3
通讯作者：
Schopfer, P
中科院分区：
文献类型：
--
作者：
Musel, G;Schindler, T;Schopfer, P
木质素是暗栽培玉米(Zen Mays L.)初生细胞壁的重要组成部分。胚芽鞘，一种幼年器官，仍处于细胞快速伸展的发育状态。胚芽鞘木质素的特征是：(I)转化为木质硫醇乙醇酸酯衍生物，(Ii)碱解后分离出聚合物片段，(Iii)对由单醇制备的脱氢聚合物具有抗体反应性，以及(Iv)鉴定木质素典型的硫代酸解产物。温和的碱处理可以从胚芽鞘细胞壁中溶解大量的木质素。对胚芽鞘和不同中胚轴组织细胞壁的硫代酸解分析表明，玉米幼苗不同部位木质素的数量和组成存在组织特异性差异，除对香豆酸和阿魏酸外，还含有愈创木酚基、丁香基和(微量)对羟基苯基。抗愈创木基/丁香基抗体识别的表位的电子显微镜免疫金标记表明，木质素存在于4天龄的胚芽鞘的所有细胞壁中。薄壁和表皮的初生壁标记弱于管状分子的次生壁增厚。在中层薄片和细胞角部未见标记，木质素表位在播种后第2天首先出现在管胞中，在第3天出现在实质中。胚芽鞘切段在H_2O_2中的孵育增加了薄壁细胞壁上可提取木质素的数量和木质素表位的丰度，木质素沉积与细胞壁中富含脯氨酸的蛋白的表位的出现在时间和空间上是相关的，但与富含羟脯氨酸的蛋白的表位的出现无关。白光或远红光照射幼苗后，胚芽鞘中木质素含量增加，与抑制伸长生长有关，而生长素的促进作用不明显。结果表明，初生细胞壁的木质化可以控制胚芽鞘的壁硬度，从而控制胚芽鞘的伸长生长。原生壁木质素可能代表限制细胞壁延伸性的延伸的多糖-多酚网络的一部分。
Lignin is an integral constituent of the primary cell walls of the dark-grown maize (Zen mays L.) coleoptile, a juvenile organ that is still in the developmental state of rapid cell extension. Coleoptile lignin was characterized by (i) conversion to lignothiolglycolate derivative, (ii) isolation of polymeric fragments after alkaline hydrolysis, (iii) reactivity to antibodies against dehydrogenative polymers prepared from monolignols, and (iv) identification of thioacidolysis products typical of lignins. Substantial amounts of lignin could be solubilized from the coleoptile cell walls by mild alkali treatments. Thioacidolysis analyses of cell walls from coleoptiles and various mesocotyl tissues demonstrated the presence of guaiacyl-, syringyl- and (traces of) p-hydroxyphenyl units besides p-coumaric and ferulic acids, There are tissue-specific differences in amount and composition of lignins from different parts of the maize seedling. Electron-microscopic immunogold labeling of epitopes recognized by a specific anti-guaiacyl/syringyl antibody demonstrated the presence of lignin in all cell walls of the 4-d-old coleoptile. The primary walls of parenchyma and epidermis were more weakly labeled than the secondary wall thickenings of tracheary elements. No label was found in middle lamellae and cell corners, Lignin epitopes appeared first in the tracheary elements on day 2 and in the parenchyma on day 3 after sowing. Incubation of coleoptile segments in H2O2 increased the amount of extractable lignin and the abundance of lignin epitopes in the parenchyma cell walls, Lignin deposition was temporally and spatially correlated with the appearance of epitopes for proline-rich proteins, but not for hydroxyproline-rich proteins, in the cell walls. The lignin content of coleoptiles was increased by irradiating the seedlings with white or far-red light, correlated with the inhibition of elongation growth, while growth promotion by auxin had no effect. It is concluded that wall stiffness, and thus extension growth, of the coleoptile can be controlled by lignification of the primary cell walls. Primary-wall lignin may represent part of an extended polysaccharide-polyphenol network that limits the extensibility of the cell walls.