脂肽对稻瘟病菌几丁质酶和葡聚糖酶的影响

 研究经比基尼链霉菌(Streptomyces bikiniensis)HD-087发酵产物脂肽处理后的稻瘟病菌(Magnaporthe grisea)菌丝体内的几丁质酶活性和β-1,3葡聚糖酶活性的变化情况,分析chit基因和β-1,3 glu基因的表达量变化,旨在探究脂肽抗稻瘟病菌的作用机理。采用HPLC分析法鉴定了S. bikiniensis HD-087产生的脂肽种类,利用荧光定量PCR技术检测稻瘟病菌菌丝中chit基因和β-1,3 glu基因mRNA的表达情况。结果表明S. bikiniensis HD-087产生的脂肽主要是伊枯草素。经EC₉₀浓度的脂肽提取物处理6 h后,稻瘟病菌菌丝中几丁质酶活性和chit基因的mRNA表达量分别比对照组上调了6.77倍和51.27倍;处理12 h后,β-1,3葡聚糖酶的活性和β-1,3 glu基因的mRNA表达量分别比对照组上调了2.44倍和14.13倍。表明脂肽能够诱导稻瘟病菌菌丝体chit基因和β-1,3 glu基因的大量表达,从而破坏细胞壁结构,推测脂肽阻遏了稻瘟病菌的细胞自噬进程。

Effects of lipopeptide on chitinase and glucanase of Magnaporthe grisea

The chitinase and β-1,3-glucanase activities in the mycelia of Magnaporthe grisea treated with lipopeptide from Streptomyces bikiniensis HD-087 were studied. In order to further study the mechanism of lipopeptides against M. grisea, the types of lipopeptides produced by S. bikiniensis HD-087 were identified by HPLC, and the mRNA expression levels of chit and β-1,3 Glu genes in the mycelia of M. grisea were detected by fluorescence real-time PCR. The main lipopeptides produced by S. bikiniensis HD-087 belong to iturin family. After being treated with lipopeptides at concentration of EC₉₀ for 6 h, chitinase activity and chit gene expression in the mycelia of M. grisea were 6.77 times and 51.27 times higher than the control group, respectively. Whe-reas, after 12 h of treatment, the activity of β-1,3-glucanase and the expression of β-1,3 Glu were 2.44 times and 14.13 times higher than the control group, respectively. The results showed that lipopeptides could induce mass expression of chit and β-1,3 Glu genes in the mycelium of M. grisea, thereby destroying the cell wall structure. It is speculated that lipopeptides inhibit the autophagy of M. grisea.