Changes of the gene expression in silkworm larvae and Cordyceps militaris at late stages of the pathogenesis

Abstract

Cordyceps militaris is an entomopathogenic fungus that forms its fruiting body. The gene expression change in C. militaris and silkworm larvae were analyzed using RNA-seq to investigate the relationship of C. militaris with the host, silkworm larvae before the death by mycosis. At 144 h after the injection of C. militaris conidia, genes encoding proteases, protease inhibitors, and cuticle proteins in the fat body of silkworm larvae were upregulated, but genes encoding lipoproteins and other proteins in hemolymph were downregulated. On the other hand, at 168 h after the injection of C. militaris conidia, genes encoding amino acid and oligopeptide transporters and permeases in C. militaris were upregulated, suggesting that C. militaris may use peptides and amino acids in silkworm larvae as a nutrient to grow in vivo. Additionally, one gene cluster composed of genes putatively involved in the degradation of phenolic substrates was also upregulated. The addition of 4,5-dichlorocatechol, an inhibitor of catechol 1,2-dioxygenase, inhibited the in vivo growth of C. militaris, Beauveria bassiana and Metarhizium anisopliae.These results also suggest that the expression of the gene cluster may be crucial for the in vivo growth of C. militaris and entomopathogenic fungi. This study will clarify how C. militaris grows in insect hosts by avoiding host's immune systems.

The Sordariomycetes: an expanding resource with Big Data for mining in evolutionary genomics and transcriptomics

“…The Sordariomycetes also include diverse entomopathogenic fungi, including the “zombie” fungus genus Cordyceps and the species of Beauveria (Cordycipitaceae, Hypocreales) and Metarhizium (Cordycipitaceae, Hypocreales), commonly used as biopesticides of pathogenic insects and arthropods. Omics-based investigation of these fungi is expanding rapidly ( Zheng et al., 2011 ; Xiao et al., 2012 ; Pattemore et al., 2014 ; Valero-Jiménez et al., 2016 ; Wang et al., 2016a ; Chen et al., 2019 ; Kato et al., 2022 ; Thananusak et al., 2022 ; Liu and Dong, 2023 ). Interestingly, some fungi, such as Metarhizium species, are capable of attacking hosts in both the plant and the animal kingdoms.…”

“…Among the pathogenic Sordariomycetes, species of Fusarium have been intensively studied for their diverse genome structures ( Brown and Proctor, 2013 ; Ma et al., 2013 ; Zhang, 2019 ; Mir et al., 2023 ). Research on entomopathogenic Sordariomycetes, represented by Cordyceps , Beauveria , and Metarhizium species, has been greatly enhanced by the availability of genomes of these species ( Gao et al., 2011 ; Pattemore et al., 2014 ; Valero-Jiménez et al., 2016 ; Kato et al., 2022 ; Liu and Dong, 2023 ; Sant Anna Iwanicki et al., 2023 ). Neurospora species have been examined as metabolic models of the biodegradation of cellulose and other plant organics ( Feldman et al., 2019 ; Liu et al., 2020 ; Wu et al., 2020 ; Huberman et al., 2021 ), as well as providing some of the most tractable models for the circadian clock and fungal responses to environmental factors, such as light and temperature ( Wang et al., 2016c ; Dekhang et al., 2017 ; Wang et al., 2018b ; Kelliher et al., 2020 ; Kelliher et al., 2023 ).…”