Benhamou N, Broglie K, Broglie R, Chet I
Département de phytologie, Faculté des sciences de l'agriculture et de l'alimentation, Université Laval, Sainte-Foy, Que., Canada.
Can J Microbiol. 1993 Mar;39(3):318-28. doi: 10.1139/m93-045.
A chitinase, purified to homogeneity from ethylene-treated bean leaves, was applied to actively growing mycelial cells of Rhizoctonia solani to evaluate a potential antifungal activity. Light microscopic investigations at 30-min intervals following enzyme exposure revealed the induction of morphological changes such as swelling of hyphal tips and hyphal distortions. More precise information concerning fungal cell alteration was obtained by ultrastructural observation and cytochemical detection of chitin distribution in fungal cell walls. Chitin breakdown was found to be an early event preceding wall disruption and cytoplasm leakage. The large amounts of chitin present in the walls of control R. solani cells and the rapid chitin hydrolysis upon chitinase treatment lead us to suggest that this polysaccharide is one of the main components of this fungal cell wall and is readily accessible to chitinase, especially in the apical zone. By 60 min after enzyme treatment, labeled molecules were observed in the vicinity of some fungal cells, suggesting the release of chitin oligosaccharides from fungal cell walls. The antifungal activity of the bean chitinase on cells of R. solani grown in culture is discussed in relation to the potential of genetically modified transgenic plants to resist attack by R. solani through an antimicrobial activity in planta.
从经乙烯处理的菜豆叶片中纯化至同质的一种几丁质酶，被应用于立枯丝核菌活跃生长的菌丝体细胞，以评估其潜在的抗真菌活性。在酶处理后每隔30分钟进行的光学显微镜观察显示，诱导了诸如菌丝顶端肿胀和菌丝扭曲等形态变化。通过超微结构观察和真菌细胞壁中几丁质分布的细胞化学检测，获得了有关真菌细胞改变的更精确信息。发现几丁质分解是细胞壁破坏和细胞质泄漏之前的早期事件。对照立枯丝核菌细胞的细胞壁中存在大量几丁质，且几丁质酶处理后几丁质迅速水解，这使我们认为这种多糖是该真菌细胞壁的主要成分之一，且易被几丁质酶作用，尤其是在顶端区域。酶处理60分钟后，在一些真菌细胞附近观察到标记分子，表明从真菌细胞壁释放出了几丁质寡糖。结合转基因植物通过植物体内抗菌活性抵抗立枯丝核菌攻击的潜力，讨论了菜豆几丁质酶对培养的立枯丝核菌细胞的抗真菌活性。
