Aspergillus flavus GPI-anchored protein-encoding ecm33 has a role in growth, development, aflatoxin biosynthesis, and maize infection
Aspergillus flavus GPI-anchored protein-encoding ecm33 has a role in growth, development, aflatoxin biosynthesis, and maize infection
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DOI：
10.1007/s00253-018-9012-7
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发表时间：
2018-06-01
影响因子：
5
通讯作者：
Abe, Keietsu
中科院分区：
文献类型：
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作者：
Chang, Perng-Kuang;Zhang, Qi;Abe, Keietsu
真菌的许多糖基磷脂酰肌醇锚定蛋白（GPI-APs）是膜酶、组织成分和细胞外基质粘附素。我们分析了8个黄曲霉GPI-AP基因家族转录组，鉴定出AFLA_040110、AFLA_063860和AFLA_113120是分析的36个家族基因中表达量最高的5个基因。前两个基因的破坏对黄曲霉的生长发育没有显著影响。相反，破坏AFLA_113120（酿酒酵母ECM33的同源物）会导致营养生长和分生条件显著降低，促进菌核生成，并改变分生孢子色素沉着。与野生型和补充菌株相比，黄曲霉ecm33零突变体主要产生黄曲霉毒素B-2，但积累了相当数量的环吡唑酸。在低浓度（25-50 μ g/mL）下，对刚果红的敏感性降低，但在高浓度（250-500 μ g/mL）下，对荧光粉的敏感性增加。细胞壁碳水化合物分析表明，突变菌株α -葡聚糖含量显著降低（p < 0.05），几丁质和-葡聚糖含量升高。在一项玉米定植研究中，该突变体的传染性受损，产生的分生孢子数量比野生型和补充菌株低3- 4倍。A. flavus Ecm33是正常细胞壁组成所必需的，在真菌的正常生长发育、黄曲霉毒素的生物合成和种子定植中起重要作用。
Many glycosylphosphatidylinositol-anchored proteins (GPI-APs) of fungi are membrane enzymes, organization components, and extracellular matrix adhesins. We analyzed eight Aspergillus flavus transcriptome sets for the GPI-AP gene family and identified AFLA_040110, AFLA_063860, and AFLA_113120 to be among the top 5 highly expressed genes of the 36 family genes analyzed. Disruption of the former two genes did not drastically affect A. flavus growth and development. In contrast, disruption of AFLA_113120, an orthologue of Saccharomyces cerevisiae ECM33, caused a significant decrease in vegetative growth and conidiation, promoted sclerotial production, and altered conidial pigmentation. The A. flavus ecm33 null mutant, compared with the wild type and the complemented strain, produced predominantly aflatoxin B-2 but accumulated comparable amounts of cyclopiazonic acid. It showed decreased sensitivity to Congo red at low concentrations (25-50 mu g/mL) but had increased sensitivity to calcofluor white at high concentrations (250-500 mu g/mL). Analyses of cell wall carbohydrates indicated that the alpha-glucan content was decreased significantly (p < 0.05), but the contents of chitin and -glucan were increased in the mutant strain. In a maize colonization study, the mutant was shown to be impaired in its infectivity and produced 3- to 4-fold lower amounts of conidia than the wild type and the complemented strain. A. flavus Ecm33 is required for proper cell wall composition and plays an important role in normal fungal growth and development, aflatoxin biosynthesis, and seed colonization.