• 한국균학회지
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• 제22권1호
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• pp.1-7
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• 1994

Several mutants which never underwent to sexual development(NSD) of Aspergillus nidulans were analyzed genetically and physiologically. They were divided into two groups according to their characterisitics of asexual development after release from aeration block. The mutants in first group proceeded asexual development immediately after removal of aeration block, while those in second group did 10 hours or more later. The NSD mutants were separated into 4 complementation groups, nsdA, nsdB, nsdC and nsdD. The nsdA and nsdD genes were linked to AcrA1 on linkage groupⅡ and pabaA1 on linkage group I, respectively. The mutant alleles were all recessive to wild type allele in heterokayon state. The mutants did not developed cleistothecia on any of carbon sources, except NSD208 which developed cleistothecia on lactose.

• Journal of Plant Biology
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• 제15권3호
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• pp.14-18
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• 1972

This paper includes a review on recent development on protoplast culture, regeneraton of plant from protoplast, and fusion of isolated protoplasts, and also describes the possibility of obtaining interspecific hybrid plants through asexual fusion of protoplasts of cells from distantly related plants which are not crossed by the ordinary sexual method.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2005년도 International Meeting of the Microbiological Society of Korea
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• pp.229.1-229
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• 2005

• The Plant Pathology Journal
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• 제30권3호
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• pp.236-244
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• 2014

The plant pathogen Fusarium graminearum causes Fusarium head blight in cereal crops and produces mycotoxins that are harmful to animals and humans. For the initiation and spread of disease, asexual and sexual reproduction is required. Therefore, studies on fungal reproduction contribute to the development of new methods to control and maintain the fungal population. Screening a previously generated transcription factor mutant collection, we identified one putative $C_2H_2$ zincfinger transcription factor, pcs1, which is required for both sexual and asexual reproduction. Deleting pcs1 in F. graminearum resulted in a dramatic reduction in conidial production and a complete loss of sexual reproduction. The pathways and gene ontology of pcs1-dependent genes from microarray experiments showed that several G-protein related pathways, oxidase activity, ribosome biogenesis, and RNA binding and processing were highly enriched, suggesting that pcs1 is involved in several different biological processes. Further, overexpression of pcs1 increased conidial production and resulted in earlier maturation of ascospores compared to the wild-type strain. Additionally, the vegetative growth of the overexpression mutants was decreased in nutrient-rich conditions but was not different from the wild-type strain in nutrient-poor conditions. Overall, we discovered that the pcs1 transcription factor positively regulates both conidiation and sexual reproduction and confers nutrient condition-dependent vegetative growth.

• 미생물학회지
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• 제49권1호
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• pp.8-16
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• 2013

sndA 유전자(AN3911) 하위에 위치하고 있는 GAL4형 전사인자를 암호화하는 유전자(AN3912)에 대해 분석하였다. 이 전사인자는 Zn(II)2Cys6 binuclear cluster DNA-binding domain 과 전사활성부위를 모두 가지고 있는 전형적 진균 특이 전사인자로서 해당 유전자는 gtfA (gal4 type transcription factor)라 명명되었다. 이 유전자의 ORF는 762개의 아미노산으로 구성되어 있고 3개의 intron이 그 안에 존재하였다. gtfA 유전자의 결실돌연변이는 무성포자생성이 감소하고 대신 유성생식기관이 증가하는 형질을 보여주었다. 과다발현균주는 높은 포도당 농도가 주어지면 유성생식이 늦어지는 형질을 나타내었다. gtfA 유전자는 영양생장 후반부와 유성분화 초기단계에서 높은 발현량을 보이고 전생활사를 통해 비교적 일정하게 발현되었다. gtfA의 전사는 일부 유성(NsdD, VeA) 및 무성(FluG, FadA, SfaD) 분화 조절자들에 의해 크게 영향을 받지 않았다. 반면 GtfA는 nsdC 유전자의 발현을 억제하는 것으로 나타났다. 종합하여 볼 때, GtfA는 분화 결정시기에 nsdC의 발현을 억제함으로써 유성분화보다는 무성분화로 유도되도록 조절 할 것으로 추정된다.

• 미생물학회지
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• 제45권4호
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• pp.312-317
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• 2009

사상성 모델 진균인 Aspergillus nidulans에 존재하는 forkhead 유전자들의 구조와 기능을 체계적으로 연구하기 위해 유전체 분석을 통해 forkhead 도메인을 가지고 있는 6개의 forkhead 유전자를 발견하였다. 이들 중 4개의 유전자들은 다른 진균에서 발견되는 forkhead 유전자들과 전반적인 유사성이 있었으나, 2개의 유전자들은 다른 종에서는 보존되어있지 않은 A. nidulans 특이적인 유전자들이었다. A. nidulans 특이적 forkhead 유전자들 중 하나인 fkhF(AN8949.2) 유전자는 염색체 7번에 위치하고 있고, ORF는 2,337 bp로 구성되어 있으며 778개의 아미노산을 암호화하고 있는 것으로 추정되었다. 예상되는 FkhF 단백질의 N-말단 부위에 보존된 forkhead 도메인을 가지고 있었으며, 이 유전자의 기능을 분석하기 위해 유전자제거 돌연변이 균주를 제조하였다. fkhF 유전자 결손돌연변이주는 유성분화 유도 조건 등을 포함한 여러 고체배지 배양 조건에서 유성분화에는 영향을 미치지 않았으나 무성포자병(conidiophore)의 생성 밀도와 성숙도에 영향을 주는 것으로 관찰되었고, 야생형과 달리 진탕배양시에 무성포자병을 형성함이 관찰되었다. 이는 fkhF 유전자가 A. nidulans의 부적절한 무성분화를 억제하고 정상적인 무성포자 성숙과정에 관여하는 유전자라는 것을 보여준다.

• Journal of Ecology and Environment
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• 제37권1호
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• pp.21-29
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• 2014

Robinia pseudoacacia has become invasively naturalized in Japan. We investigated the role of sexual reproduction in the development of R. pseudoacacia riparian forests along the Chikumagawa River in Japan, by using five chloroplast (cpSSR) and seven nuclear (nSSR) markers. We identified eight chloroplast haplotypes and 147 nuclear genotypes from 619 R. pseudoacacia trees sampled in three plots (Plots A, B, and C) and along two line transects (Lines D and E). CpSSR analyses showed that multiple maternal lines were distributed along the river, and that some haplotypes from different populations overlapped. In addition, while Plots A and B were separated by a short distance, only these two plots exhibited genetic differentiation in the haplotypes. In the nSSR analysis, all pairwise $F_{ST}$ values among the three plots were significantly different from zero. Kinship analysis based on nSSR markers revealed that kinship connected many individuals to another individual from the same plot. These results indicate that seed dispersal near to mother trees contributes to the fine-scale genetic structure of R. pseudoacacia riparian forests. Our results indicate that sexual reproduction, in addition to asexual reproduction, is a major contributor to the fine-scale formation of R. pseudoacacia forests.

• 한국균학회지
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• 제38권2호
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• pp.160-166
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• 2010

모델 사상성 진균 Aspergillus nidulans는 분화과정을 연구하는 진핵세포 시스템으로 사용되어 왔다. 이러한 분화과정은 매우 다양한 유전자들의 발현을 통하여 조절되며 이와 관련된 다양한 전사요소들의 기능이 연구되어 왔다. 이들 중 forkhead 유전자는 일반적으로 감수분열 및 세포주기 조절에 중요한 역할을 하는 것으로 알려져 왔으며 A. nidulans에서도 유사한 기능을 하리라 예상되어 왔다. 이와 관련된 연구를 위하여 A. nidulans 유전체에 존재하는 6개의 forkhead 유전자를 발견, 확보하였고, 최근에는 효모 및 다른 진균에서는 발견되지 않는 A. nidulans 특이적 forkhead 유전자인 fkhF의 구조와 기능이 분석된 바 있다. 본 연구에서는 fkhF와 매우 유사한 단백질 서열을 가지고 있는 fkhE(AN2025.3) 유전자의 기능을 분석하였다. 본 유전자의 기능을 분석하기 위해 RT-PCR을 통하여 cDNA 서열을 분석한 결과 약 3종류의 서로 다른 mRNA가 존재하는 것이 밝혀졌고 이는 alternative splicing에 의한 것으로 추정되었다. 이들 3종류의 mRNA중 한 종류만 정상적인 ORF를 가지고 있으며 조사한 전체 cDNA 발현의 61%를 차지하였다. fkhE 유전자는 718개의 아미노산을 암호화하는 하나의 ORF를 가지고 있었으며 N 말단에 보존된 forkhead 도메인을 가지고 있었다. fkhE 유전자를 제거한 유전자 제거 돌연변이 균주는 fkhF와 유사하게 고체배지에서는 무성포자의 형성이 저해되었으나 유성분화에는 별다른 영향을 미치지 않았으며 액체 진탕배양에서는 야생형과 다르게 무성포자병(conidiophore)이 형성되었다. 이러한 결과는 fkhE 유전자가 무성분화에 관련되었음을 보여준다.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2014년도 추계학술대회 및 정기총회
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• pp.15-15
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• 2014

Fusarium graminearum (teleomorph Gibberella zeae) is an important plant pathogen that causes head blight of major cereal crops such as wheat, barley, and rice, as well as causing ear and stalk rot on maize worldwide. Plant diseases caused by this fungus lead to severe yield losses and accumulation of harmful mycotoxins in infected cereals [1]. Fungi utilize spore production as a mean to rapidly avoid unfavorable environmental conditions and to amplify their population. Spores are produced sexually and asexually and their production is precisely controlled. Upstream developmental activators consist of fluffy genes have been known to orchestrate early induction of condiogenesis in a model filamentous fungus Aspergillus nidulans. To understand the molecular mechanisms underlying conidiogenesis in F. graminearum, we characterized functions of the F. graminearum fluffy gene homologs [2]. We found that FlbD is conserved regulatory function for conidiogenesis in both A. nidulans and F. graminearum among five fluffy gene homologs. flbD deletion abolished conidia and perithecia production, suggesting that FlbD have global roles in hyphal differentiation processes in F. graminearum. We further identified and functionally characterized the ortholog of AbaA, which is involved in differentiation from vegetative hyphae to conidia and known to be absent in F. graminearum [3]. Deletion of abaA did not affect vegetative growth, sexual development, or virulence, but conidium production was completely abolished and thin hyphae grew from abnormally shaped phialides in abaA deletion mutants. Overexpression of abaA resulted in pleiotropic defects such as impaired sexual and asexual development, retarded conidium germination, and reduced trichothecene production. AbaA localized to the nuclei of phialides and terminal cells of mature conidia. Successful interspecies complementation using A. nidulans AbaA and the conserved AbaA-WetA pathway demonstrated that the molecular mechanisms responsible for AbaA activity are conserved in F. graminearum as they are in A. nidulans. F. graminearum ortholog of Aspergillus nidulans wetA has been shown to be involved in conidiogenesis and conidium maturation [4]. Deletion of F. graminearum wetA did not alter mycelial growth, sexual development, or virulence, but the wetA deletion mutants produced longer conidia with fewer septa, and the conidia were sensitive to acute stresses, such as oxidative stress and heat stress. Furthermore, the survival rate of aged conidia from the F. graminearum wetA deletion mutants was reduced. The wetA deletion resulted in vigorous generation of single-celled conidia through autophagy-dependent microcycle conidiation, indicating that WetA functions to maintain conidia dormancy by suppressing microcycle conidiation in F. graminearum. In A. nidulans, FlbB physically interacts with FlbD and FlbE, and the resulting FlbB/FlbE and FlbB/FlbD complexes induce the expression of flbD and brlA, respectively. BrlA is an activator of the AbaA-WetA pathway. AbaA and WetA are required for phialide formation and conidia maturation, respectively [5]. In F. graminearum, the AbaA-WetA pathway is similar to that of A. nidulans, except a brlA ortholog does not exist. Amongst the fluffy genes, only fgflbD has a conserved role for regulation of the AbaA-WetA pathway.

• Mycobiology
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• 제49권3호
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• pp.258-266
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• 2021

The velvet regulators VosA and VelB are primarily involved in spore maturation and dormancy. Previous studies found that the VosA-VelB hetero-complex coordinates certain target genes that are related to fungal differentiation and conidial maturation in Aspergillus nidulans. Here, we characterized the VosA/VelB-inhibited developmental gene vidD in A. nidulans. Phenotypic analyses demonstrated that the vidD deleted mutant exhibited defect fungal growth, a reduced number of conidia, and delayed formation of sexual fruiting bodies. The deletion of vidD decreased the amount of conidial trehalose, increased the sensitivity against heat stress, and reduced the conidial viability. Moreover, the absence of vidD resulted in increased production of sterigmatocystin. Together, these results show that VidD is required for proper fungal growth, development, and sterigmatocystin production in A. nidulans.