Inbar J, Chet I
Otto Warburg Center for Agricultural Biotechnology, Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, Israel.
Microbiology (Reading). 1995 Nov;141 ( Pt 11):2823-9. doi: 10.1099/13500872-141-11-2823.
The induction of chitinolytic enzymes in the biocontrol agent Trichoderma harzianum during parasitism on Sclerotium rolfsii and the role of fungal-fungal recognition in this process were studied. A change in the chitinolytic enzyme profile was detected during the interaction between the fungi, grown in dual culture on synthetic medium. Before coming into contact with each other, both fungi contained a protein with constitutive 1,4-beta-N-acetylglucosaminidase activity. As early as 12 h after contact, the chitinolytic activity in S. rolfsii disappeared, while that of T. harzianum (a protein with a molecular mass of 102 kDa, CHIT 102) greatly increased. After 24 h of interaction, the activity of CHIT 102 diminished concomitantly with the appearance of a 73 kDa 1,4-beta-N-acetylglucosaminidase, which became clear and strong at 48 h. This phenomenon did not occur if the S. rolfsii mycelium was autoclaved prior to incubation with T. harzianum, suggesting its dependence on vital elements from the host. Cycloheximide inhibited this phenomenon, indicating that de novo synthesis of enzymes is taking place in Trichoderma during these stages of the parasitism. A biomimetic system based on the binding of a purified surface lectin from the host S. rolfsii to nylon fibres was used to dissect the effect of recognition. An increase in CHIT 102 activity was detected, suggesting that the induction of chitinolytic enzymes in Trichoderma is an early event which is elicited by the recognition signal (i.e. lectin-carbohydrate interactions). It is postulated that recognition is the first step in a cascade of antagonistic events which triggers the parasitic response in Trichoderma.
研究了生防菌哈茨木霉在寄生罗尔夫斯核盘菌过程中几丁质分解酶的诱导作用以及真菌 - 真菌识别在此过程中的作用。在合成培养基上进行共培养时，检测到两种真菌相互作用过程中几丁质分解酶谱的变化。在彼此接触之前，两种真菌都含有一种具有组成型1,4-β-N-乙酰氨基葡萄糖苷酶活性的蛋白质。接触后仅12小时，罗尔夫斯核盘菌中的几丁质分解活性就消失了，而哈茨木霉（一种分子量为102 kDa的蛋白质，CHIT 102）的几丁质分解活性大幅增加。相互作用24小时后，CHIT 102的活性随着一种73 kDa的1,4-β-N-乙酰氨基葡萄糖苷酶的出现而降低，该酶在48小时时变得清晰且活性增强。如果在与哈茨木霉共培养之前将罗尔夫斯核盘菌的菌丝体进行高压灭菌，这种现象就不会发生，这表明它依赖于宿主中的活性成分。放线菌酮抑制了这种现象，表明在寄生的这些阶段，木霉中正在进行酶的从头合成。基于宿主罗尔夫斯核盘菌纯化的表面凝集素与尼龙纤维结合的仿生系统被用于剖析识别的作用。检测到CHIT 102活性增加，这表明木霉中几丁质分解酶的诱导是由识别信号（即凝集素 - 碳水化合物相互作用）引发的早期事件。据推测，识别是一系列拮抗事件的第一步，它触发了木霉中的寄生反应。
