Morissette D C, Seguin P, Jabaji-Hare S H
Department of Plant Science, McGill University, Sainte-Anne-de-Bellvue, Canada.
Can J Microbiol. 2006 Nov;52(11):1103-9. doi: 10.1139/w06-068.
The regulation of the gene encoding the extracellular chitinase sechi44 produced by the mycoparasite Stachybotrys elegans was studied using real-time quantitative reverse-transcription polymerase chain reaction. Alteration of sechi44 expression was observed when S. elegans was in interaction with its host, Rhizoctonia solani, and also when the mycoparasite was grown on minimal media amended with different carbon and nitrogen sources. Direct contact with R. solani leading to mycoparasitism significantly up-regulated the expression of sechi44, although the analysis showed that sechi44 was constitutively expressed but at substantially lower levels. In addition, the study of sechi44 over 12 days showed that its expression followed a cyclical pattern with peaks every 2 days, which suggests that this gene has a role not only in mycoparasitism but also in growth. The addition of external carbon sources, such as N-acetylglucosamine, chitin, and R. solani cell wall (simulated mycoparasitism), triggered an increase in the expression of sechi44, which varied with time and carbon source. Among the carbon sources examined, N-acetylglucosamine induced the highest increase in sechi44 transcript levels. The addition of high concentrations of glucose and ammonium triggered a decrease of sechi44 expression, suggesting that sechi44 is subject to glucose and ammonium repression.
利用实时定量逆转录聚合酶链反应，研究了真菌寄生菌雅致葡萄穗霉产生的细胞外几丁质酶sechi44编码基因的调控。当雅致葡萄穗霉与其寄主立枯丝核菌相互作用时，以及当该真菌寄生菌在添加了不同碳源和氮源的基本培养基上生长时，均观察到sechi44表达的变化。与立枯丝核菌的直接接触导致真菌寄生作用显著上调了sechi44的表达，尽管分析表明sechi44是组成型表达，但水平要低得多。此外，对sechi44在12天内的研究表明，其表达呈周期性模式，每2天出现峰值，这表明该基因不仅在真菌寄生中起作用，而且在生长中也起作用。添加外部碳源，如N-乙酰葡糖胺、几丁质和立枯丝核菌细胞壁（模拟真菌寄生），会引发sechi44表达的增加，其随时间和碳源而变化。在所检测的碳源中，N-乙酰葡糖胺诱导sechi44转录水平增加最多。添加高浓度的葡萄糖和铵会引发sechi44表达的下降，这表明sechi44受到葡萄糖和铵的抑制。
