一株生防烟管菌几丁质酶表达及抗真菌活性

Expression and antifungal activity of chitinase from biocontrol agent Bjerkandera adusta

摘要:

为了探究烟管菌BK-1的生物防治潜力，本研究测试了一株具有生防菌活性的烟管菌BK1的抗病效果，并使用RT-qPCR分析了该菌株的8个细胞壁裂解酶基因在与不同病原真菌对峙培养中的表达水平，结果表明，在应对链格孢、茄链格孢、尖孢镰刀菌和灰葡萄孢这4种病原真菌时，几丁质酶基因BaCHIB表达上调了27.3至50.3倍，远高于其他7个基因. BaCHIB属于糖苷水解酶18家族（GH 18），并具有Chic_BD结构域，属于B类几丁质酶（CHIB）. 结合基因表达谱分析，该基因诱导表达上调情况的出现与抗病效果的出现高度同步. 外源表达蛋白BaCHIB显示出较高的几丁质酶活性，且表现出对多种植物病原真菌，包括链格孢，链格孢和灰葡萄孢显著的抗真菌活性，显示其对部分病原真菌具有拮抗能力.

Abstract:

In order to explore the biological control potential of Bjerkandera adusta BK-1, this study tested the disease resistance effect of BK-1 with the antifungal activity. And used RT-qPCR to analyze the expression levels of eight cell-wall lyase genes of B. adusta strain BK-1. The results showed that in response to six pathogenic fungi (Alternaria alternata, Alternaria alternata f. sp. mali, Alternaria solani, Alternaria tenuissima, Fusarium oxysporum and Botrytis cinerea), the expression of the chitinase gene BaCHIB was up-regulated by 27.3 to 50.3 times expression of,which is much higher than the other seven candidate genes. BaCHIB belongs to the glycoside hydrolase 18 family (GH 18), and has the Chic_BD (aromatic chitin/cellulose-binding site residues) domain, a domain that belongs to the chitinase subgroup B (CHIB). Combined with the analysis of disease resistance in planta, the up-regulation of the gene induced expression is highly synchronized with the appearance of disease resistance. And the exogenously expressed protein BaCHIB extracted from the Pichia pastoris expression system showed high chitinase and significant antifungal activity against a variety of plant-pathogenic fungi, including Alternaria alternata, Alternaria solani and Botrytis cinerea. This result showed that BaCHIB has a fungicide activity.