Comparative analysis of biocontrol agent Trichoderma asperellum ACCC30536 transcriptome during its interaction with Populus davidiana × P. alba var. pyramidalis.

After exposure to with Populus davidiana × P. alba var. pyramidalis, the expression of genes in Trichoderma asperellum were compared in four transcriptomes. The top 20 high expression genes included six heat shock proteins and three hydrophobins, indicating that Trichoderma can rapidly adapt to environment stresses and elicit a plant defense response. The genes, involved in the interaction between Trichoderma and plant, showed an increasing expression level, for example sugar transporters, EPL1s, endoxylanases, pectin lyases, and nitrilases. Interestingly, sugar transporters also showed high expression when T. asperellum was cultured on medium lacking a carbon substrate, which would contribute to T. asperellum's survival and domination in ecological niche competition. And the genes related to mycoparasitism were expressed abundantly following T. asperellum's interaction with PdPap, indicating the PdPap induction could enhance the mycoparasitic ability of T. asperellum. Twelve chitinases and five glucanases showed higher expression in transcriptome Cs, indicating that T. asperellum secretes both types of enzyme before interacting with pathogens, allowing T. asperellum to implement mycoparasitism and obtain more energy. Many novel transcripts were obtained in each transcriptome, which may play important roles in the biocontrol process of T. asperellum. Interestingly, T. asperellum undergo constitutive alternative splicing in the biocontrol process: Seven biocontrol genes were alternative spliced via intron retention. qRT-PCR analysis proved that intron retention is negatively associated with the expression of chitinase, oligopeptide transporters, and beta-lactamase. However, the percentage of MAPK intron retention was quite low, suggesting that intron retention has little effect on the function of MAPK.