| 研究課題/領域番号 |
20F20103
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| 研究機関 | 岡山大学 |
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研究代表者 |
Ivan Galis 岡山大学, 資源植物科学研究所, 教授 (90360502)
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| 研究分担者 |
WARI DAVID 岡山大学, 資源植物科学研究所, 外国人特別研究員
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| 研究期間 (年度) |
2020-09-25 – 2023-03-31
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| キーワード | brown planthopper / rice / microbial symbiont |
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| 研究実績の概要 |
The isolation of microbes from brown planthopper honeydew was completed and biological activity was examined. Most of isolates could induce defense responses in rice cultured cells. Selected microbial isolates (6) were then used in field experiment with Nipponbare rice in Kurashiki field. Specifically, rice plants were repeatedly treated with microbial isolates in two-week-intervals and herbivore damage/presence was screened on these plants relative to untreated controls. Only small differences were observed in herbivore density but plants treated with isolate 6-22 shoved higher damage from chewing pests, suggesting that some microbial agents from brown planthopper honeydew could compromise rice defense in the field. This existence of effector-like microbes for suppression of plant defense in sucking pest honeydew will be further examined in 2022.
In the second part of this research, diversity of microbes was examined using sequencing of DNA from honeydew. Samples from 6 regions in Japan and reference laboratory strain were used and showed that major types of microbes can be found in all samples. It suggests that microbes are closely associated with brown planthoppers and serve some essential functions in the insect pest. The most abundant species representing almost 60 percent of all sequences belonged to Bacillales and Pseudomonadales. The results will be further verified in 2022.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
The experiments progress as expected. We completed all main tasks planned for 2021. There is no problem to report at present.
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| 今後の研究の推進方策 |
In the final six months we will conduct second field trial with Nipponbare rice and treat them with six selected microbial strains to confirm results obtained in 2021. The mechanisms of compromised defense of rice after treatment with 6-22 strain will be examined using analytical approaches. In particular, changes in plant hormone levels and defense metabolites will be examined by LC-MS/MS. Additionally, effects of microbes on indirect rice defense systems will be examined by analysis of volatile emissions from rice treated with microbial strain 6-22.
In the second part, honeydew samples will be collected again from a long storage culture of brown planthoppers kept in the laboratory. The spectrum and abundance of microbes will be re-examined to expose possible adaptation/conversion of microbiota in brown planthoppers due to external environmental factors like laboratory cultivation.
Results will be summarized and presented in form of poster presentation at international meeting of International Society for Chemical Ecology in Kuala Lumpur, Malaysia. Publications will be compiled and submitted to peer review journals during FY2022.
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