Whole RNA-sequencing and gene expression analysis of Trichoderma harzianum Tr-92 under chlamydospore-producing condition.

BACKGROUND

Trichoderma is one of the most important biocontrol fungi, which could produce mycelia, conidiospores, and chlamydospores three types of propagules under different conditions. Chlamydospores are produced in harsh conditions in various fungi, and may be more resistant to adverse conditions. However, the knowledge associated with the mechanism of chlamydospore formation remained unclear in Trichoderma.

OBJECTIVES

This study is aimed to explore the essential genes and regulatory pathways associated with chlamydospore formation in Trichoderma.

METHODS

The culture condition, survival rate, and biocontrol effects of chlamydospores and conidiospores from Trichoderma.harzianum Tr-92 were determined. Furthermore, the whole transcriptome profiles of T. harzianum Tr-92 under chlamydospore-producing and chlamydospore-nonproducing conditions were performed.

RESULTS

T. harzianum Tr-92 produced chlamydospores under particular conditions, and chlamydospore-based formulation of T. harzianum Tr-92 exhibited higher biocontrol ability against Botrytis cinerea in cucumber than conidoiospore-based formulation. In the transcriptome analysis, a total of 2,029 differentially expressed genes (DEGs) were identified in T. harzianum Tr-92 under chlamydospore-producing condition, compared to that under chlamydospore-nonproducing condition. GO classification indicated that the DEGs were significantly enriched in 284 terms among biological process, cellular components and molecular function categories. A total of 19 pathways were observed with DEGs by KEGG analysis. Furthermore, fifteen DEGs were verified by quantitative real-time PCR, and the expression profiles were consistent with the transcriptome data.

CONCLUSION

The results would provide a basis on the molecular mechanisms underlying Trichoderma sporulation, which would assist the development and application of fungal biocontrol agents.