Laboratory of Environmental Microbiology, Brazilian Agricultural Research Corporation, Embrapa Environment, Jaguariúna, Brazil.
Department of Entomology and Acarology, "Luiz de Queiroz" College of Agriculture/University of São Paulo (ESALQ/USP), Piracicaba, Brazil.
Front Cell Infect Microbiol. 2021 Mar 24;11:644372. doi: 10.3389/fcimb.2021.644372. eCollection 2021.
Culturing the entomopathogenic fungus, , under high glucose concentrations coupled with high aeration results in a fungal developmental shift from hyphal growth to mostly blastospores (yeast-like cells). The underlying molecular mechanisms involved in this shift remain elusive. A systematic transcriptome analysis of the differential gene expression was preformed to uncover the fungal transcriptomic response to osmotic and oxidative stresses associated with the resulting high blastospore yield. Differential gene expression was compared under moderate (10% w/v) and high (20% w/v) glucose concentrations daily for three days. The RNAseq-based transcriptomic results depicted a higher proportion of downregulated genes when the fungus was grown under 20% glucose than 10%. Additional experiments explored a broader glucose range (4, 8, 12, 16, 20% w/v) with phenotype assessment and qRT-PCR transcript abundance measurements of selected genes. Antioxidant, calcium transport, conidiation, and osmosensor-related genes were highly upregulated in higher glucose titers (16-20%) compared to growth in lower glucose (4-6%) concentrations. The class 1 hydrophobin gene () was highly expressed throughout the culturing. is known to be involved in spore coat rodlet layer assembly, and indicates that blastospores or another cell type containing hydrophobin 1 is expressed in the haemocoel during the infection process. Furthermore, we found implications of the HOG signaling pathway with upregulation of homologous genes and for all fermentation time points under hyperosmotic medium (20% glucose). These findings expand our knowledge of the molecular mechanisms behind blastospore development and may help facilitate large-scale industrial production of blastospores for pest control applications.
在高葡萄糖浓度和高通气条件下培养昆虫病原真菌会导致真菌发育从菌丝生长转变为主要是芽生孢子（酵母样细胞）。涉及这种转变的潜在分子机制仍不清楚。进行了系统的转录组分析，以揭示与高芽生孢子产量相关的渗透和氧化应激下真菌的转录组反应。在中度（10%w/v）和高（20%w/v）葡萄糖浓度下，每天比较 3 天的差异基因表达。与在 10%葡萄糖下生长相比，在 20%葡萄糖下生长时，下调基因的比例更高。额外的实验探索了更广泛的葡萄糖范围（4、8、12、16、20%w/v），并进行了表型评估和选定基因的 qRT-PCR 转录丰度测量。与在较低葡萄糖浓度（4-6%）下生长相比，在较高葡萄糖滴度（16-20%）下，抗氧化剂、钙转运、分生孢子形成和渗透压感受器相关基因高度上调。类 1 亲水性蛋白基因（）在整个培养过程中高度表达。已知参与孢子外壳棒状层的组装，并且表明在感染过程中亲水性蛋白 1 在血腔中表达芽生孢子或另一种含有亲水性蛋白 1 的细胞类型。此外，我们发现高渗介质（20%葡萄糖）下 HOG 信号通路的同源基因和的上调与所有发酵时间点都有关，这表明 HOG 信号通路可能参与了渗透压应激反应。这些发现扩展了我们对芽生孢子发育背后的分子机制的认识，并可能有助于促进大规模工业生产用于害虫控制应用的芽生孢子。
