The Trichodermin Biosynthetic Genes In Trichoderma Taxi And Function Of Tri3 In The Biosynthesis Of Trichodermin

Trichoderma taxi, which can produce an antifungal bioactive metabolite called trichodermin, is one of endophytic fungi isolated from Taxus mairei. With application prospect of developing into bio-pesticide, trichodermin can effectively inhibit the growth of many pathogenic fungi, such as Rhizoctonia solani and Botrytis cinerea. During fermentation process, the amount of trichodermin raises at the beginning of fermentation but drop at a certain time point. Thus, the research is intended to analyze the trichodermin biosynthesis pathway, as well as the related genes, and to get the T. taxi engineering strain using gene modification, break the bottleneck of trichodermin fermentation, consequently, high production of trichodermin can be achieved.According to the genome sequencing result, the trichothecene biosynthetic genes Tri3, Tri4, Tri6, Tri10, Trill, Tri12, Tril4 forms the Tri gene cluster in T. taxi. And Tri genes have high homology with their according genes of T. arundinaceum, T. brevicompactum, Fusarium sporotrichioides and F. graminearum. The Tri genes transcription initiation sites and the length of the coding sequence is very similar.The Tri3 gene of T. arundinaceum may encode the enzyme which catalyzes the reaction of trichodermol acetylation to HA on C-4 position. As the high homology of Tri3 gene between T. taxi and T. arundinaceum, the Tri3 gene of T. taxi is speculated to have the function of encoding the enzyme of last reaction (trichodermol acetylation to trichodermin on C-4 position). Gene deletion mutant Tt△Tri3 of T. taxi was obtained using the method of ATMT. Compared with the wild type, the content of trichodermin decreased significantly in the fermentation broth of Tt△Tri3, but the trichodermol content is as much as the wild type. And inhibition activity of fermentation broth to pathogenic fungi decreased. Therefore, it is deducted that TtTri3 is related with the biosynthesis of trichodermin, and can profoundly affect trichodermin production to some extend, but Tri3 may not be the only gene that control the process of trichodermol to trichodermin. Or, Tri3 encoded the enzyme regulate the process of trichodermol to trichodermin, the reaction was blocked and then triggered some bypass reactions during fermentation, indirectly caused the minor production of trichodermin.The research of Tri genes related in trichodermin biosynthesis is crucial toclarify the mechanisms of reaction and expression during the process of trichodermin biosynthesis and to understand the evolutionary process of Tri gene clusters, consequently, contribute to the development of biopesticide.