Jung A Kim

Integrating coalescent and phylogenetic approaches to delimit species in the lichen photobiont Trebouxia

The accurate assessment of species boundaries in symbiotic systems is a prerequisite for the study of speciation, co-evolution and selectivity. Many studies have shown the high genetic diversity of green algae from the genus Trebouxia, the most common photobiont of lichen-forming fungi. However, the phylogenetic relationships, and the amount of cryptic diversity of these algae are still poorly understood, and an adequate species concept for trebouxiophycean algae is still missing. In this study we used a multifaceted approach based on coalescence (GMYC, STEM) and phylogenetic relationships to assess species boundaries in the trebouxioid photobionts of the lichen-forming fungus Lasallia pustulata. We further investigated whether putative species of Trebouxia found in L. pustulata are shared with other lichen-forming fungi. We found that L. pustulata is associated with at least five species of Trebouxia and most of them are shared with other lichen-forming fungi, showing different patterns of species-to-species and species-to-community interactions. We also show that one of the putative Trebouxia species is found exclusively in association with L. pustulata and is restricted to thalli from localities with Mediterranean microclimate. We suggest that the species delimitation method presented in this study is a promising tool to address species boundaries within the heterogeneous genus Trebouxia.

Agrobacterium tumefaciens -Mediated Transformation of the Lichen Fungus, Umbilicaria muehlenbergii

Transformation-mediated mutagenesis in both targeted and random manners has been widely applied to decipher gene function in diverse fungi. However, a transformation system has not yet been established for lichen fungi, severely limiting our ability to study their biology and mechanism underpinning symbiosis via gene manipulation. Here, we report the first successful transformation of the lichen fungus, Umbilicaria muehlenbergii, via the use of Agrobacterium tumefaciens. We generated a total of 918 transformants employing a binary vector that carries the hygromycin B phosphotransferase gene as a selection marker and the enhanced green fluorescent protein gene for labeling transformants. Randomly selected transformants appeared mitotically stable, based on their maintenance of hygromycin B resistance after five generations of growth without selection. Genomic Southern blot showed that 88% of 784 transformants contained a single T-DNA insert in their genome. A number of putative mutants affected in colony color, size, and/or morphology were found among these transformants, supporting the utility of Agrobacterium tumefaciens-mediated transformation (ATMT) for random insertional mutagenesis of U. muehlenbergii. This ATMT approach potentially offers a systematic gene functional study with genome sequences of U. muehlenbergii that is currently underway.

A new reducing polyketide synthase gene from the lichen-forming fungus Cladonia metacorallifera

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 metacorallifera was employed in the isolation and characterization of a polyketide synthase gene (CmPKS1). The complete sequence information for CmPKS1 was 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 CmPKS1 was expressed preferentially in the early growth stage of the axenically cultured mycobiont. Furthermore CmPKS1 expression was found to be dependent on the carbon sources and concentrations in the medium.

Diversity of endophytic fungi associated with bryophyte in the maritime Antarctic (King George Island)

Abstract Bryophytes comprise one of the richest microfungal microhabitats in the Antarctic environment. The maritime Antarctic is very vulnerable to rapid environmental change caused by global warming. The aim of this study was to investigate the importance of bryophytes as a microhabitat for fungal species in the maritime Antarctic by surveying endophytic fungal diversity from several bryophytes including Andreaea sp., Barbilophozia hatcheri, Chorisodontium aciphyllum, Polytrichum alpinum, Polytrichumstrictum, Sanionia uncinata, and Warnstorfia sarmentosa. We collected 13 bryophyte samples at four localities on Barton Peninsula, King George Island. In total, 31 endophytic fungi morphotypes were isolated from bryophyte tissues by a thorough surface sterilization method. Using internal transcribed spacer sequence analysis, 16 endophytic fungal strains belonging to Ascomycota (12), Basidiomycota (1), Oomycota (1), and Zygomycota (2) phyla were obtained. Our results suggest the presence of a diverse range of fungal species even in a very limited area, and those bryophytes play an important role in conserving fungal diversity in this harsh environment. Growth rate measurements at a wide range of temperatures confirmed that most of the fungal strains were both mesophilic and psychrotolerant. This is the first report of endophytic fungi in Antarctic moss tissue by fluorescence in situ hybridization.

Draft Genome Sequence of Lichen-Forming Fungus Cladonia metacorallifera Strain KoLRI002260

ABSTRACT The lichen-forming fungus Cladonia metacorallifera strain KoLRI002260 is capable of producing a number of secondary metabolites, including usnic, didymic, and squamatic acids, which have antitumor, antioxidant, and antibiotic activities. The draft genome assembly has a size of 36,682,060 bp, with a G+C content of 44.91%, and consists of 30 scaffolds.

Antifungal activity of eucalyptus-derived phenolics against postharvest pathogens of kiwifruits

Antifungal activities of natural substrances from Eucalyptus darlympleana, E. globules, E. gunnii and E. unigera were evaluated against postharvest pathogens of kiwifruits, Botrytis cinerea, Botryosphaeria dothidea, and Diaporthe actinidiae, to screen effective natural substances as an alternative to chemical fungicides. Methanol extract of the Eucalyptus trees showed strong antagonistic activity against the pathogenic fungi. Among them, E. unigera and E. darlympleana effectively inhibited mycelial growth of the pathogens. For chemical identification of the antifungal substances, the methanol extract of E. darlympleana leaves was successively partitioned with CH(2)Cl(2), EtOAc, n-BuOH and H(2)O. Among the fractions, CH,Cl, and n-BuOH showed strong inhibitory activity of mycelial growth of the fungi. Five compounds were isolated from EtOAc and n-BuOH fractions subjected to SiO(2) column chromatography. Two phenolic compounds (gallic acid and 3,4-dihydroxy-benzoic acid) and three flavonoid compounds (quercetin, quercetin-3-O-alpha-L-rhamnoside, quercetin-3-O-beta-D-glucoside) were identified by (1)H-NMR and (13)C-NMR spectroscopy. Among them, only gallic acid was found to be effective in mycelial growth and spore germination of B. cinerea at relatively high concentrations. The results suggest that gallic acid can be a safer and more acceptable alternative to current synthetic fungicides controlling soft rot decay of kiwifruit during postharvest storage.

Draft Genome Sequence of Umbilicaria muehlenbergii KoLRILF000956, a Lichen-Forming Fungus Amenable to Genetic Manipulation

ABSTRACT Umbilicaria muehlenbergii strain KoLRILF000956 is amenable to Agrobacterium tumefaciens-mediated transformation (ATMT), making it the only known genetically tractable lichen-forming fungus to date. We report another advancement in lichen genetics, a draft genome assembly for U. muehlenbergii with a size of 34,812,353 bp and a GC content of 47.12%, consisting of seven scaffolds.

Draft Genome Sequence of Cladonia macilenta KoLRI003786, a Lichen-Forming Fungus Producing Biruloquinone.

ABSTRACT The lichen-forming fungus Cladonia macilenta strain KoLRI003786 is capable of producing an acetylcholinesterase inhibitor, biruloquinone, which effectively prevents neurodegeneration in Alzheimers disease. Laying the foundation to unravel the biruloquinone biosynthetic pathway, we present the 37.11-Mb draft genome sequence of strain KoLRI003786.

Draft Genome Sequence of Lichen-Forming Fungus Caloplaca flavorubescens Strain KoLRI002931

ABSTRACT Here we report a draft genome sequence of Caloplaca flavorubescens strain KoLRI002931, isolated from the bark of a gingko tree at Mt. Deogyu, Muju, South Korea. The genome sequence is 34,455,815 bp, with a GC content of 41.89%, consisting of 36 scaffolds.

Plant Hormones Promote Growth in Lichen-Forming Fungi

The effect of plant hormones on the growth of lichen-forming fungi (LFF) was evaluated. The use of 2,3,5-triiodobenzoic acid and indole-3-butyric acid resulted in a 99% and 57% increase in dry weight of the lichen-forming fungus Nephromopsis ornata. The results suggest that some plant hormones can be used as inducers or stimulators of LFF growth for large-scale culture.