www.helmholtz-hzi.de Introduction The species of the Chaetosphaeriaceae (Chaetosphaeriales, Sordariomycetes, Ascomycota) are microscopic asexually reproducing fungi, some of which belong to the life cycle of sexual morphs with macroscopic fruit bodies (~300 μm diam) perceptible as “black dots” on the surface of decaying plants. They are invisible to most of the people and difficult to find even by a trained eye. In addition, they are usually hard to cultivate and slow growing, what make them difficult to study. Traditionally, they are reported from the decaying plant matter in the forest habitat and some exhibit endophytic lifestyle . Surprisingly, analysis of metabarcoding data showed that they are also common soil fungi, dwelling in a bulk soil in grasslands and croplands. There are about 44 genera classified into this family with monographs available for several genera, but with very little knowledge about their biology. Studies showed that Chaetosphaeriaceae members are important degraders of lignocellulose in wood, litter and soil and have rich structural diversity of natural compounds (e.g. terpenoids, cyclic peptides, naphthoquinones, lactones, lipopeptides, xanthones). Three unpublished and unannotated draft genomes of Chaetosphaeriaceae are available (1000 fungal genome project). Nevertheless, the information about the genetic background of the basic pathways is missing in this fungal lineage. The same is true for the whole Chaetosphaeriales. Our study is filling this gap using analysis of genomes from 16 species. Genome assembly statics of 16 species from the family Chaetosphaeriaceae Comparison of CAZymes classes within the Chaetosphaeriaceae Homology analysis of predicted pyrichalasin H biosynthesis gene cluster in M. ciliata, M. caesia, and P.grisea Conclusion: In this study, we introduced the genomes of sixteen Chaetosphaeriaceae species. The quality of those genomes were assessed, and their carbohydrate-active enzymes (CAZymes) were annotated. There are more than 800 genes that encode CAZymes from each species. The genome mining of the analyzed members of the Chaetosphaeriaceae species revealed a high diversity of biosynthetic pathways that far outmatches the number of compounds known from the individual species. The genome sequences generated in this work will enablea broad range of investigations including studies on fungal evolution, population dynamics, biodegradation and also biosynthesis of secondary metabolites. Acknowledgement: The department Microbial Drugs is gratefully acknowledged for financial support of TC. The work was also supported by ESF project "International mobility of researchers of the Institute of Microbiology of the CAS, v.v.i. No 2" registration number CZ.02.2.69/0.0/0.0/18_053/0017705. First insight into Chaetosphaeriaceae biology using genomic Tian Cheng1,2, František Sklenář2, Martina Réblová2, Tobias Busche3, Marc Stadler1, Jörn Kalinowski3, and Miroslav Kolařík2 1Helmholtz Centre for Infection Research, Inhoffenstr 7, 38124 Braunschweig, Germany. 2Institute of Microbiology, the Czech Academy of Sciences, Vídeňská 1083, 142 20 Praha, Czech Republic. 3Center for Biotechnology (CeBiTec), Bielefeld University, Universitätsstr 25, D-33615 Bielefeld, Germany. References (1) Réblová M, Barr ME, Samuels GJ. (1999) Chaetosphaeriaceae, a new family for Chaetosphaeria and its relatives. Sydowia 51(1): 49–70. (2) Wijayawardene NN, Hyde KD, Al-Ani LKT, et al. (2020) Outline of Fungi and fungus-like taxa. Mycosphere 11(1): 1060–1456. (3) Wang C, Hantke V, Cox R, et al. (2019) Targeted Gene Inactivations Expose Silent Cytochalasans in Magnaporthe grisea NI980. Org. Lett. 21(11): 4163-4167. (4) Kjærbølling I, Vesth T, Frisvad J, et al. (2018) Linking secondary metabolites to gene clusters through genome sequencing of six diverse. Proc. Natl. Acad. Sci. U.S.A. 115(4): E753-E761. Tian.Cheng@Helmholtz-hzi.de Number of identified enzymes are displayed. (GT: glycosyl transferase, GH: glycoside hydrolas