Genomic characterization provides new insights int...
Xincong Kang1，2，3# Chichuan Liu4# Pengyuan Shen2，3 Liqin Hu2，3 Runmao Lin4Jian Ling4 Xingyao Xiong1，2，4 Bingyan Xie4 Dongbo Liu1，2，3，5*
1.Horticulture and Landscape College，Hunan Agricultural University，Changsha，Hunan，P.R.China；
2.Hunan Provincial Key Laboratory of Crop Germplasm Innovation and Utilization，Hunan Agricultural University，Changsha，Hunan，P.R.China；
3.State Key Laboratory of Subhealth Intervention Technology，Changsha，Hunan，P.R.China；(https://www.daowen.com)
4.Institutes of Vegetables and Flowers，Chinese Academy of Agricultural Sciences，Beijing，P.R.China；
5.Hunan Co-Innovation Center for Utilization of Botanical Functional Ingredients，Changsha，Hunan，P.R.China.
Abstract：A reliable source of Huperzine A(Hup A)meets an urgent need due to its wide use in Alzheimer's disease treatment.In this study，we sequenced and characterized the whole genomes of two HupA-producing endophytes，Penicillium polonicum hy4 and Colletotrichum gloeosporioides Cg01，to clarify the mechanism of HupA biosynthesis.The whole genomes of hy4 and Cg01 were 33.92Mb and 55.77Mb，respectively.We compared the differentially expressed genes(DEGs)between the induced group(with added extracts of Huperzia serrata)and a control group.We focused on DEGs with similar expression patterns in hy4 and Cg01.The DEGs identified in GO(Gene ontology)and KEGG(Kyoto Encyclopedia of Genes and Genomes)pathways were primarily located in carbon and nitrogen metabolism and nucleolus，ribosome，and rRNA processing.Furthermore，we analyzed the gene expression for HupA biosynthesis genes proposed in plants，which include lysine decarboxylase(LDC)，copper amine oxidase(CAO)，polyketides synthases(PKS)，etc.Two LDCs，one CAO，and three PKSs in Cg01 were selected as prime candidates for further validation.We found that single candidate biosynthesis-gene knock-out did not influence the Hup A production，while both LDC gene knock-out led to increased Hup A production.These results reveal that Hup A biosynthesis in endophytes might differ from that proposed in plants，and imply that the Hup A-biosynthesis genes in endophytic fungi might co-evolve with the plant machinery rather than being acquired through horizontal gene transfer(HGT).Moreover，we analyzed the function of the differentially expressed epigenetic modification genes.Hup A production of the histone acetyltransferase(HAT)deletion mutantΔCgSAS-2 was not changed，while that of the histone methyltransferase(HMT)and histone deacetylase(HDAC)deletion mutantsΔCgClr4，ΔCgClr3，andΔCgSir2-6 was reduced.Recovery of Hup A-biosynthetic ability can be achieved by retrocomplementation，demonstrating that HMT and HDACs associated with histone modification are involved in the regulation of HupA biosynthesis in endophytic fungi.This is the first report on epigenetic modification in high value secondary metabolite-producing endophytes.These findings shed new light on HupA biosynthesis and regulation in Hup A-producing endophytes and are crucial for industrial production of Hup A from fungi.
Keywords：endophyte，genome，differentially expressed genes，biosynthesis，histone modification，gene knockout