Freimoser Florian M, Screen Steven, Bagga Savita, Hu Gang, St Leger Raymond J
Department of Entomology, University of Maryland, 4112 Plant Sciences Building, College Park, MD 20742, USA.
Microbiology (Reading). 2003 Jan;149(Pt 1):239-47. doi: 10.1099/mic.0.25761-0.
Expressed sequence tag (EST) libraries for Metarhizium anisopliae, the causative agent of green muscardine disease, were developed from the broad host-range pathogen Metarhizium anisopliae sf. anisopliae and the specific grasshopper pathogen, M. anisopliae sf. acridum. Approximately 1,700 5' end sequences from each subspecies were generated from cDNA libraries representing fungi grown under conditions that maximize secretion of cuticle-degrading enzymes. Both subspecies had ESTs for virtually all pathogenicity-related genes cloned to date from M. anisopliae, but many novel genes encoding potential virulence factors were also tagged. Enzymes with potential targets in the insect host included proteases, chitinases, phospholipases, lipases, esterases, phosphatases and enzymes producing toxic secondary metabolites. A diverse array of proteases composed 36 % of all M. anisopliae sf. anisopliae ESTs. Eighty percent of the ESTs that could be clustered into functional groups had significant matches (E<10(-5)) in other ascomycete fungi. These included genes reported to have specific roles in pathogens with plant or vertebrate hosts. Many of the remaining ESTs had their best BLAST match among animal, plant and bacterial sequences. These include genes with plant and microbial counterparts that produce potent antimicrobials. The abundance of transcripts discovered for different functional groups varied between the two subspecies of M. anisopliae in a manner consistent with ecological adaptations of the two pathogens. By hastening gene discovery this project has enhanced development of improved mycoinsecticides. In addition, the M. anisopliae ESTs represent a significant contribution to the extensive database of sequences from ascomycetes that are saprophytes or plant and vertebrate pathogens. Comparative analyses of these sequences is providing important information about the biology and evolutionary history of this clade.
绿僵菌病的病原体金龟子绿僵菌的表达序列标签（EST）文库，是从广宿主范围的病原体金龟子绿僵菌变种金龟子绿僵菌和特定的蝗虫病原体金龟子绿僵菌变种蝗绿僵菌构建而来。从代表在能使角质层降解酶分泌最大化的条件下生长的真菌的cDNA文库中，产生了来自每个亚种的约1700个5'端序列。两个亚种都有迄今从金龟子绿僵菌克隆的几乎所有与致病性相关基因的EST，但也标记了许多编码潜在毒力因子的新基因。在昆虫宿主体内有潜在作用靶点的酶包括蛋白酶、几丁质酶、磷脂酶、脂肪酶、酯酶、磷酸酶以及产生有毒次生代谢产物的酶。各种各样的蛋白酶占所有金龟子绿僵菌变种金龟子绿僵菌EST的36%。80%能够聚类到功能组的EST在其他子囊菌中有显著匹配（E<10(-5)）。这些包括据报道在具有植物或脊椎动物宿主的病原体中具有特定作用的基因。许多其余的EST在动物、植物和细菌序列中与最佳BLAST匹配。这些包括具有植物和微生物对应物且能产生强效抗菌剂的基因。在金龟子绿僵菌的两个亚种之间，为不同功能组发现的转录本丰度以与这两种病原体的生态适应性一致的方式有所不同。通过加速基因发现，该项目促进了改良杀真菌剂的开发。此外，金龟子绿僵菌的EST对来自作为腐生菌或植物和脊椎动物病原体的子囊菌的广泛序列数据库做出了重大贡献。对这些序列的比较分析正在提供有关该进化枝的生物学和进化历史的重要信息。
