title: rDNA-targeted PCR primers and FISH probe in the detection of Ophiocordyceps sinensis hyphae and conidia.
abstract: Ophiocordyceps sinensis (Berk.) Sung, Sung, Hywel-Jones & Spatafora (syn. Cordyceps sinensis) one of the entomopathogenic fungi, is a rare Traditional Chinese Medicine (TCM) found in the Qinghai-Tibetan Plateau. Polymerase Chain Reaction (PCR) and Fluorescence in situ hybridization (FISH) methods are necessary to identify the mycelia or spores of O. sinensis from its habitat and to monitor its dispersal, colonization and infectivity. To develop both primers and probe specific to O. sinensis, ribosomal DNA (rDNA) amplified with universal primers from O. sinensis genomic DNA and seven closely related fungi were sequenced. According to these sequences, the upper and lower primers (OsT-F and OsT-R) were designed within internal transcribed spacer region 1 (ITS1) and ITS2 and flanked by universal primers ITS5 and ITS4, respectively. The designed primers were used for general PCR, touchdown PCR, or both together with the universal primers for nested-touchdown PCR. The results showed that only the extracted DNA of O. sinensis was specifically amplified. The sensitivity of nested-touchdown PCR with extracted DNA of O. sinensis is as low as 10(-14)g (10 fg) and at least 1000 times higher than the other PCR methods. In addition, Cy5-labeled probe (OsLSU) for cytoplasmic LSU rRNA was hybridized with the ascospores of O. sinensis. It showed a strong red fluorescence throughout the whole cell but did not cross-react with other entomopathogenic fungi. Taken together, these methods were useful for studying the biology and ecology of O. sinensis.
authors.affiliation: Food and Health Engineering Research Center of State Education Ministry, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhong
authors.forename: Qingyun
authors.initials: Q
authors.lastname: Peng
authors.forename: Lili
authors.initials: L
authors.lastname: Qi
authors.forename: Wei
authors.initials: W
authors.lastname: Lei
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
mesh_terms: D017931:DNA Primers / Q000235:genetics; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics*; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D025301:Hyphae / Q000235:genetics / Q000302:isolation & purification*; D006999:Hypocreales / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D008969:Molecular Sequence Data; D009172:Mycology / Q000379:methods*; D015345:Oligonucleotide Probes / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA; D013172:Spores, Fungal / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D017931:DNA Primers; D004271:DNA, Fungal; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D015345:Oligonucleotide Probes