Screening of laccase-producing isolates among plant pathogenic fungi | 植物病原真菌产漆酶菌株的筛选

Chinese. 【目的】从常见植物病原真菌中筛选具有漆酶活性的病原菌,对相对酶活力较高的菌株进行漆酶致病力测定,为深入研究漆酶在植物病原真菌致病过程中所发挥的作用及病菌的扩展机理奠定基础。【方法】以2,2’-连氮-双[3-乙基苯并噻唑-6-磺酸](ABTS)为底物,通过平板显色反应筛选得到产漆酶的病原菌,同时利用苯胺蓝(Azure-B)脱色法确定目标菌株降解木质素作用,采用分光光度计法在420 nm下测定漆酶活性,最后利用组织病理学分析漆酶对病原菌致病力的影响。【结果】从20种重要植物病原真菌中筛选得到10种产漆酶的病原菌,且均具有降解木质素的作用,对其中6种颜色变化不同的病原菌进行漆酶活力测定,发现玉米大斑病菌的胞内漆酶活力最高,为18.984 U?mL-1,小孢拟盘多毛孢的胞外漆酶活力最高,为0.919 U?mL-1。致病力测定表明,在玉米大斑病菌的致病过程中,漆酶可以氧化玉米叶片并能够促进病原菌在寄主组织中的扩散。【结论】在产漆酶的植物病原真菌中,漆酶大多以胞内酶形式存在,并具有降解木质素的作用,漆酶可以促进玉米大斑病菌在寄主组织中扩展。

English. 【Objective】 Screening isolates from plant pathogenic fungi which be able to produce laccase and determining the laccase activity could give a deep insight into functional research for the pathogenicity of laccase. 【Method】 Using 2,2’-azino-bis[3-ethylbenzthiazoline-6-sulfonic acid] (ABTS) as substrate, isolates with laccase were screened from plant pathogenic fungi through the plate-color reaction and confirmed that these isolates had a role in lignin degradation using aniline blue (Azure-B). Laccase activity of six different isolates was compared using spectrophotometer at 420 nm. The effect of pathogenicity from laccase was analyzed using the histopathology. 【Result】 Ten isolates with a role in lignin degradation were screened from twenty plant pathogenic fungi. Setosphaeria turcica and Pestalotiopsis microspora contained the highest intracellular and extracellular laccase activity, which were 18.984 and 0.919 U?mL-1, respectively. The analysis of histopathology in S. turcica showed that maize leaves were oxidated by laccase which could accelerate the extention of pathogen against the host. 【Conclusion】 Most of the laccase in the plant pathogenic fungi were intracellular laccase which had a role in lignin degradation. In this study, laccase of S. turcica was found that could contribute to the expansion of pathogen in the host tissue.