title: The intronic minisatellite OsMin1 within a serine protease gene in the Chinese caterpillar fungus Ophiocordyceps sinensis.
abstract: Repetitive DNA sequences make up a significant portion of all genomes and may occur in intergenic, regulatory, coding, or even intronic regions. Partial sequences of a serine protease gene csp1 was previously used as a population genetic marker of the Chinese caterpillar fungus Ophiocordyceps sinensis, but its first intron region was excluded due to ambiguous alignment. Here in this study, we report the presence of a minisatellite OsMin1 within this intron, where a 20(19)-bp repeat motif is duplicated two to six times in different isolates. Fourteen intron alleles and 13 OsMin1 alleles were identified among 125 O. sinensis samples distributed broadly on the Tibetan Plateau. Two OsMin1 alleles were prevalent, corresponding to either two or five repeats of the core sequence motif. OsMin1 appears to be a single locus marker in the O. sinensis genome, but its origin is undetermined. Abundant recombination signals were detected between upstream and downstream flanking regions of OsMin1, suggesting that OsMin1 mutate by unequal crossing over. Geographic distribution, fungal phylogeny, and host insect phylogeny all significantly affected intron distribution patterns but with the greatest influence noted for fungal genotypes and the least for geography. As far as we know, OsMin1 is the first minisatellite found in O. sinensis and the second found in fungal introns. OsMin1 may be useful in designing an efficient protocol to discriminate authentic O. sinensis from counterfeits.
authors.affiliation: School of Life Sciences, Shanxi University, Taiyuan, 030006, China. zhangyj2008@sxu.edu.cn.
authors.forename: Yong-Jie
authors.initials: YJ
authors.lastname: Zhang
authors.affiliation: School of Life Sciences, Shanxi University, Taiyuan, 030006, China.
authors.forename: Jun-Xiu
authors.initials: JX
authors.lastname: Hou
authors.affiliation: Institute of Applied Chemistry, Shanxi University, Taiyuan, 030006, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Microbiology, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
authors.forename: Georg
authors.initials: G
authors.lastname: Hausner
authors.affiliation: State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China. liuxz@im.ac.cn.
authors.forename: Xing-Zhong
authors.initials: XZ
authors.lastname: Liu
authors.affiliation: Sunshine Lake Pharma Co., LTD, Dongguan, 523808, China.
authors.forename: Wen-Jia
authors.initials: WJ
authors.lastname: Li
mesh_terms: D000818:Animals; D001483:Base Sequence; D005656:Fungal Proteins / Q000235:genetics*; D016681:Genome, Fungal; D005838:Genotype; D006999:Hypocreales / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D007438:Introns; D018598:Minisatellite Repeats; D008969:Molecular Sequence Data; D009036:Moths / Q000382:microbiology*; D010802:Phylogeny; D057057:Serine Proteases / Q000235:genetics*; D018609:Tibet
chemical_list: D005656:Fungal Proteins; D057057:Serine Proteases
keywords: Intron; Minisatellite; Ophiocordyceps sinensis; Unequal crossing over; csp1