| Project/Area Number |
10306004
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
植物保護
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| Research Institution | Mie University |
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Principal Investigator |
KUNOH Hitoshi Mie University, Faculty of Bioresources, Professor, 生物資源学部, 教授 (20024573)
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| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI Issei Mie University, Faculty of Bioresources, Associate Professor, 生物資源学部, 助教授 (90205451)
TAKAMATSU Susumu Mie University, Faculty of Bioresources, Professor, 生物資源学部, 教授 (20260599)
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| Project Period (FY) |
1998 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥41,250,000 (Direct Cost: ¥39,300,000、Indirect Cost: ¥1,950,000)
Fiscal Year 2001: ¥8,450,000 (Direct Cost: ¥6,500,000、Indirect Cost: ¥1,950,000)
Fiscal Year 2000: ¥4,700,000 (Direct Cost: ¥4,700,000)
Fiscal Year 1999: ¥6,200,000 (Direct Cost: ¥6,200,000)
Fiscal Year 1998: ¥21,900,000 (Direct Cost: ¥21,900,000)
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| Keywords | powdery mildew / pathogenicity / resistance / susceptibility / divergence / obligate parasite |
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| Research Abstract |
(1) Infection of plants by airborne fungi initiates from adhesion of spores onto host surfaces. Conidia of barley powdery mildew, Blumeria graminis, releases extracellular matrix (ECM) immediately after they contact host surfaces. ECM is involved in adhesion of spores and determination of emergence sites of germ tubes. Thus, ECM holds an initial key of pathogenesis of this fungus. Physiological analyses revealed that this fungus secreted various cell wall degrading enzymes in ECM and molecular biological studies showed that genes of these enzymes were expressed during morphogenesis of conidia step by step. Another physiological study showed that accessibility-inducing factor could be synthesized or activated in barley coleoptiles by successful infection of B. graminis. Characters of this factor were partially determined. Further studies are still necessary for purification of this factor and determination of its molecular structure.
(2) We found the importance of actin cytoskeleton in d
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efense mechanism against fungal invasion, using several actin inhibitors. These results revealed the importance of temporal and spatial control of resistance machinery. In animal cells, Rac small GTPases play a central role in a remodeling of actin cytoskeleton. To investigate a function of plant Rac GTPases, we cloned tobacco Rac genes and overexpressed in tobacco plants. Increased sensitivity to salicylic acid in overexpressors suggest that plant Rac proteins are involved in an induction of systemic acquired-resistance.
(3) The nucleotide sequences of the nuclear rDNA were determined for 33 powdery mildew taxa spanning 15 genera to infer the phylogenetic relationships for these fungi. Phylogenetic analyses revealed that Uncinula septata is placed in the primitive base to the large clade composed of all other powdery mildew taxa. Powdery mildews excluding U. septata are split into five major lineages. The mycelioid appendage which has long been regarded as an ancestral character may be a derived character as a result of an event that may have occurred multiple times independently due to convergence. Euoidium-type anamorph and clavate appressorial germ tube are considered to be ancestral characters to Pseudoidium-type anamorph and lobed germ tube. Ectophytic nature and polyascal cleistothecia are also regarded as ancestral features to endophytic nature and monoascal cleistothecia. Less
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