病原体胁迫下植物细胞壁的变化

Change in the Cell Walls of Plants on Pathogen Stress

植物细胞壁是阻止病原体侵入的第一道结构屏障。植物在受病原体胁迫时,细胞壁的结构和组分变化是一种早期的防御反应,这种变化往往伴随胼胝质、富含羟脯氨酸糖蛋白和木质素的合成。植物受病原体感染时,胼胝质于乳突和胞间连丝等处大量积累。胁迫信号通过影响胼胝质合成酶和β-1,3-葡聚糖酶基因的转录表达,最终调节细胞壁中胼胝质的量。另外,病原体胁迫可诱导植物细胞内抗病性相关的木质素合成酶活性增强和细胞壁木质化。木质素和胼胝质在细胞壁的积累,加强了细胞壁的机械强度和堵塞病原体在细胞间扩散的通道,从而限制病原体进一步侵入原生质和在组织中的繁衍。植物细胞壁中富含羟脯氨酸糖蛋白(HRGP)的积累也可由病原体和一些非病原体激发子诱导,并作为结构屏障和凝集素起到抗病作用。

The cell walls of plants are the first structural barriers to prevent are challenged by pathogen, the change pathogens invade. When the plants on structures and component of the ceU walls is an early defense response, which may accompany by synthesis of callose, lignin and Hydroxyproline-rich glycoprotein （HRGP）. When plants are infected with pathogens, massive accumulation of callose in papillae and plasmodesmata are observed. Stress signals affect transcriptional expression of callose synthase and β-1,3 -glucanase gene, and ultimately regulate the amount of callose in cell wall. In addition, the pathogen stress can induce increase of lignin synthesis activity relat- ed to plant defense response and cell wall lignification. Accumulation of lignin and callose in the cell wails of plants causes the enhanced mechanical strength of the cell walls and blocks the channel of pathogen proliferation between two ceils. HRGP accumulation in the cell wails of plants may also be induced by pathogens and elicitors. The cell wall HRGP may play a key role in plant defense reaction.