Grant-in-Aid for International Scientific Research.
|Research Institution||The University of Tokyo|
TAKAGI Masamichi Department of Biotechnology, Faculty of Agriculture, The University of Tokyo, Professor, 農学部, 教授 (50018339)
HWANG CherーW Agricultural Science and Technology Inst, Resercher
RYU JinーChan Agricultural Science and Technology Inst, Director
EUN MooーYung Agricultural Biotechnology Institute R. D, Director
堀内 裕之 東京大学, 農学部, 助手 (00209280)
MOO Yung Eui Agricultural Science and Technology Inst, Director
PARK InーCheo Agricultural Science and Technology Inst, Resercher
高谷 直樹 東京大学, 農学部・学術振興会, 特別研究
RYU Jin-Chang Agricultural Science and Technology Institute R.D.A.
HWANG Cher-Won Agricultural Science and Technology Institute R.D.A.
HORIUCHI Hiroyuki Department of Biotechnology
TAKAYA Naoki Department of Biotechnology
EUIM Moo Yung Agricultural Science and Technology Institute R.D.A.
PARK In-Cheol Agricultural Science and Technology Institute R.D.A.
|Project Fiscal Year
1994 – 1995
Completed(Fiscal Year 1995)
|Budget Amount *help
¥5,500,000 (Direct Cost : ¥5,500,000)
Fiscal Year 1995 : ¥2,500,000 (Direct Cost : ¥2,500,000)
Fiscal Year 1994 : ¥3,000,000 (Direct Cost : ¥3,000,000)
|Keywords||chitin synthase / Aspergillus / Rhizopus / tip growth / chitinase / conidiation / キチン合成酵素 / 先端生長 / キチナーゼ / 胞子形成|
In Japanese side, we investigated the functions of chitin synthases in tip growth of filamentous fungi. We have isolated four chitin synthase genes (chsA,chsB,chsC,and chsD) from Aspergillus nidulans which belongs to Ascomycete filamentous fungi and two genes (chs1 and chs2) from Rhizopus oligosporus which belongs to Zygomycete filamentous fungi. When we disrupted each one of four chitin synthase genes in the genome of A.nidulans, we detected no difference of the phenotype of these disruptants from that of wild type strain except for the chsB gene disruptant. The tip growth of chsB gene disruptant was severely defected. We constructed each kind of double gene disruptant from the chsA,chsC,and chsD gene disruptants. The frequency of conidiation of the chsA and chsC double gene disruptant and chsA and chsC double gene disruptant were 0.002% and 10% of that of wild type strain, respectively. To test the function of chsB gene product in the conidiation, .open reading frame of chsB gene was
fused to alcA gene promoter whose expression was regulated by the carbon source in the medium. When the expression of chsB gene was repressed at the conidiation stage, the frequency of conidiation decreased about one-tenth of that of wild type strain. Thus, all of chs gene products are required at the stage of conidiation. The density of hyphae of chsA and chsC double gene disruptant was very rare. It suggests that the gene products of chsA and chsC also function in the hyphae growth.
We have isolated a chitinase gene (chiA) from A.nidulans by PCR method and disrupted the gene. The disruptant of chiA gene grew and formed conidia as well as wild type strain. To investigate the phase of expression of the gene, we fused lacZ gene of Escherichia coli to chiA gene and introduced it into A.nidulans. The expression of chiA gene at the conidiation stage was twice as strong as the hyphae growth stage. Thus, it is suggested that chiA gene product function at the both stage.
In Korean side, to construct the host-vector system in the plant pathogenic fungi, Pyricularia oryzae, they have isolated some auxotrophic mutants of P.oryzae. They have also isolated a PCR fragment of chitin synthase gene from genomic DNA of P.oryzae whose function in plant pathogenicity is being investigated in Korea.
These works have been done in a cooperative manner between our group in Japan and the Korean group. Less