Comparative Analysis Of Selection Pressure In Trichoderma

Trichoderma consists of many species and strains. Because of their remarkable activities in biological control, they have been widely used to control the growth of many fungal species. Research on the biocontrol activities of Trichoderma species has been rather active in recent years. This thesis research focuses on two newly isolated Trichoderma hamatum strains YYH13 and YYH16 that show striking differences in their ability in biological control and cellulose degradation. It has been demonstrated that YYH13 has much greater strength in biocontrol than YYH16 does. In order to identify candidate genes important for biocontrol, we have sequenced, assembled, and annotated these two genomes. Using these newly established resources, I aimed to identify candidate genes by examining the evolutionary pressure on the genes in the GH family, which are important in cell wall degradation. My analysis identified 36 sites with positive selection pressure, affecting three genes in YYH13 and a single gene in YYH16. One important gene in YYH13 is subtilisin. All of these genes that have positive selection pressure may be important in enabling YYH13 has stronger activities in biocontrol.Through comparative analysis of the genomes of two Trichoderma hamatum strains YYH13 and YYH16, we have found genes that under positive selection pressure. Further molecular study on the functional contribution of these genes may facilitate the understanding differences of YYH13 and YYH16 in biocontrol and,further more, mechanisms underlying biocontrol in Trichoderma.