2005 Fiscal Year Final Research Report Summary
Cytological and Molecular Biological Analyses of Mechanisms of Signal Recognition and Host Specificity at Incipient Infection Stage
| Project/Area Number |
12052214
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Biological Sciences
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| Research Institution | MIE UNIVERSITY |
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Principal Investigator |
KUNOH Hitoshi Mie Univ., Fac.Bioresources, 生物資源学部, 教授 (20024573)
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| Co-Investigator(Kenkyū-buntansha) |
CHE Fang-Sik Nara Frontier Scientific Techn. University, Dept. of Bioscience, Assistant Prof., バイオサイエンス研究科, 助手 (00263442)
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| Project Period (FY) |
2000 – 2002
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| Keywords | powdery mildew / extracellular material / adhesion / inaccessibility / flagellin / Acidovorax avenae / microarray / resistant response |
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| Research Abstract |
Powdery mildew conidia were known to release extracellular materials (ECM)immediately after contact to hydrophobic membranes. In this study, Blumeria graminis hordei and B.g.tritici, Erysiphe pisi were confirmed to release ECM on host surfaces. ECM contributes to adhesion of conidia and determination of the emergence site of germtubes. Immuno electron and confocal microscopies revealed that materials were moved from conidia to host epidermis and vice versa via ECM within 30 min after conidial contact. Epidermal cells of barley that contacted ECM of B.g.tritici and E.pisi (both nonpathogens to barley) were directed towards inaccessibility within 6-7 h after conidial contact, while those that contacted ECM of B.g.hordei (pathogen to barley) were directed towards neither accessibility nor inaccessibility. These results show that signal transduction and host response initiate immediately after conidium-host cell contact. The host range of Acidovorax avenae is wide among monocotyledonous but individual strains can infect only one or a few host species. Recently we reported that incompatible strain of A.avenae caused the resistance response, but compatible strain did not. We also reported that the resistance response was induced by flagellin from the incompatible strain. To investigate the mechanism of rice defense response induced by the incompatible strain and the role of flagellin on this defense induction, rice cDNA microarray analysis was performed. The microarray analysis showed that induction of 25 genes was regulated by the incompatible flagellin perception. We also investigated induction specificity of resistant response between incompatible and compatible flagellins. Induction analysis of resistant response in cultured rice cells using purified flagellins and recombinant flagellins showed that the flagellin specificity is involved in the post-translational modification of flgaellins.
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