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Tip Growth of Plant-Pathogenic Fungi and Tip-Chitin Metabolism

植物病原真菌的尖端生长和尖端甲壳素代谢

基本信息

批准号：
06044062
负责人：
TAKAGI Masamichi
金额：
$ 3.52万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06044062/
关键词：
chitin synthase Aspergillus Rhizopus tip growth chitinase conidiation

项目摘要

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 … More 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

在日本方面，我们研究了几丁质酶在丝状真菌顶端生长中的作用。我们从子囊菌纲丝状真菌构巢曲霉中分离到4个几丁质合成酶基因（chsA、chsB、chsC和chsD），从接合菌纲丝状真菌少孢根霉中分离到2个几丁质合成酶基因（chs 1和chs 2）。当我们分别破坏构巢曲霉基因组中的四个几丁质合成酶基因时，我们检测到除了chsB基因破坏物之外，这些破坏物的表型与野生型菌株的表型没有差异。chsB基因阻断剂对茎尖生长有严重影响。我们从chsA、chsC和chsD基因破坏子中构建了每种双基因破坏子。chsA和chsC双基因突变株和chsA和chsC双基因突变株的产孢频率分别为野生型菌株的0.002%和10%。为了验证chsB基因产物在产孢过程中的功能，我们对chsB基因的开放阅读框进行了克隆， ...更多信息与alcA基因启动子融合，其表达受培养基中碳源的调控。当chsB基因的表达在分生孢子阶段被抑制时，分生孢子的频率下降约为野生型菌株的十分之一。因此，所有的chs基因产物都需要在分生孢子阶段。chsA和chsC双基因干扰物的菌丝密度非常低。本研究利用PCR方法从构巢曲霉中分离到一个几丁质酶基因chiA，并对其进行了基因敲除。chiA基因的破坏株与野生型菌株一样生长并形成分生孢子。为了研究该基因的表达时相，我们将大肠杆菌的lacZ基因与chiA基因融合，并将其导入构巢曲霉。chiA基因在分生孢子形成期的表达量是菌丝生长期的2倍。因此，chiA基因产物在这两个阶段都发挥作用。在韩国，为了在植物病原真菌Pyricularia pyramidae中构建宿主-载体系统，他们分离出了一些营养缺陷型的水稻疫霉突变体。他们还从韩国正在研究其在植物致病性中的功能的P. p.的基因组DNA中分离了几丁质合成酶基因的PCR片段。这些工作是我们日本小组和韩国小组合作完成的。少