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Lichens produce unique polyketide secondary metabolites including depsides, depsidones, dibenzofurans and depsones. The biosynthesis of these compounds is governed by polyketide synthase (PKS), but the mechanism via which they are produced has remained unclear until now. We reported the 6-methylsalicylic acid synthase (6-MSAS) type of PKS gene, which is a member of the fungal-reducing PKSs. A cultured mycobiont of Cladonia metacoralliferawas employed in the isolation and characterization of a polyketide synthase gene (CmPKS1). The complete sequence information for CmPKS1was acquired via the screening of a Fosmid genomic library with a 456 bp fragment corresponding to part of the acyl transferase (AT) domain as a probe. CmPKS1 contains β-ketoacyl synthase (KS), AT, dehydratase (DH), ketoreductase (KR) and phosphopantetheine attachment site (PP) domains.: The domain organization of CmPKS1 (KS-AT-DH-KR-PP) is a typical 6-MSAS-type PKS, and the results of phylogenetic analysis showed that CmPKS1 grouped with other fungal-reducing PKSs. Quantitative real time PCR analyses showed that CmPKS1was expressed preferentially in the early growth stage of the axenically cultured mycobiont. Furthermore CmPKS1expression was found to be dependent on the carbon sources and concentrations in the medium.

A survey was conducted of the rust fungus Gymnosporangiumin Korea. We recollected previously known species, namely Gymnosporangium asiaticum, G. clavariiforme, G. globosum, G. japonicumand G. yamadae. Gymnosporangium nidus-avisand G. sabinaeare reported for the first time from Korea, and two new species, G. monticolasp. nov. and G. unicornesp. nov., are recognized. Previous single reports of G. miyabeiand G. shiraianumcould not be confirmed. The LSU rDNA was sequenced from freshly collected specimens. Phylogenetic analyses show that species of Gymnosporangiumform a monophyletic group with strong bootstrap support within the rust fungi. The two new species are unique based on both A and B molecular as well as morphological characteristics. Analyses of phenotypic characters mapped onto the phylogenetic tree show that teliospore length followed by telia shape and telia length are conserved; these are morphological characters useful in differentiating species of Gymnosporangium. Each of the nine species of Gymnosporangiumin Korea is described and illustrated, and keys based on aecia and telia stages are provided. Lectotype specimens for several names described in Gymnosporangiumare designated.

Characteristics and structures of mt SSU rDNA were investigated for the phylogenetic study of Ganoderma.Phylogenetic information was concentrated mostly in the V1, V4, V5, V6 and V9 variable domains, but informative sites in conserved domains also significantly contributed in resolving phylogenetic relationships between Ganodermagroups. Secondary structure information of variable domains was found to be a useful marker in delineation of phylogenetic groups. Strains of Ganodermaspecies used in this study were divided into six monophyletic groups. Ganoderma colossusmade a distinct basal lineage from other Ganodermaspecies and Tomophagus,created for G. colosuss,appeared to be a valid genus. Ganoderma applanatumand G. lobatumclassified in subgenus Elfvingiamade a monophyletic group. Ganoderma tsugaefrom North America and G. valesiacumfrom Europe, both living on conifers, were closely related. Ganoderma oregonenseand strains labeled G. lucidumfrom Europe and Canada were grouped with G. tsugaeand G. valesiacum.Strains labeled G. lucidumliving on hardwoods from the United States and Taiwan were grouped with G. resinaceum, G. pfeifferiand G. subamboinensevar. laevisporum,and they all produced chlamydospores. Two strains labeled G. lucidumand three strains labeled G. resinaceumfrom America were concluded to be conspecific. Strains labeled G. lucidumfrom Korea and Japan were monophyletic and were distinguished from strains labeled G. lucidumfrom Europe and North America. Host relationships and the presence of chlamydospores in culture proved to be important characteristics in the systematics as well as the phylogenetic relationships of Ganoderma.

There has been a systematic need to seek adequate phylogenetic markers that can be applied in phylogenetic analyses of fungal taxa at various levels. The mitochondrial small subunit ribosomal DNA (mt SSU rDNA) is generally considered to be one of the molecules that are appropriate for phylogenetic analyses at a family level. In order to obtain universal primers for polypores of Hymenomycetes, mt SSU rRNA genes were cloned from Bjerkandera adusta, Ganoderma lucidum, Phlebiopsis gigantea, and Phellinus laevigatusand their sequences were determined. Based on the conserved sequences of cloned genes from polypores and Agrocybe aegerita, PCR primers were designed for amplification and sequencing of mt SSU rDNAs. New primers allowed effective amplification and sequencing of almost full-sized genes from representative species of polypores and related species. Phylogenetic relationships were resolved quite efficiently by mt SSU rDNA sequences, and they proved to be more useful in phylogenetic reconstruction of Ganodermathan nuclear internal transcribed spacer (ITS) rDNA sequences.

A series of 1-aryl-1-(1H-1,2,4-triazol-1-yl)alkyl-1-silacyclopentanes has been synthesized by four-step reactions starting from 1-chloroalkyltrichlorosilane and tested for fungicidal activities in vitro for ten fungi and in vivo for four fungi occurring in rice, cucumber, tomato etc. Biological activities of the title compounds are strongly dependent upon the p-substituent on the phenyl group in the following order: F>Cl>Ph>OEt>H. Especially, 1-p-fluorophenyl-1-[1-(1H-1,2,4-triazol-1-yl)alkyl]-1-silacyclopentanes (alkyl=methyl or ethyl) showed significant fungicidal activity with a broad spectrum comparable to flusilazole in in-vivo assay. © 1998 SCI.

AbstractAn improved procedure for preparing PCR cloning vectors was developed. This procedure includes the incorporation of adapters to create XcmI restriction enzyme sites in pBluescript II SK(+) vectors, digestion with XcmI followed by further digestion of the small fragment produced by XcmI digestion with additional enzymes, and purification with PCR purification kits. Using this procedure, PCR cloning vectors with high ligation efficiencies and low blue or false-positive colonies were obtained.

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