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Studies on the Potato Scab Disease in Taiwan-Biological Characteristics of the Pathogen and an Attempted Biocontrol by Antagonistic Bacilli
|作者:||曾德賜||關鍵字:||應用研究;Potato Common Scab;園藝, 植物保護類;馬鈴薯瘡痂病;生物特性;生物防治;Biological Characteristics;Biocontrol||摘要:||
先前計劃工作中，針對近二年來在本省中南部栽培馬鈴薯爆發之瘡痂病病原經檢討其生物學與病原性特徵，並利用拮抗性枯草桿菌益生性菌株測試其防治管理此病害之應用性；初步成果已證實由罹病薯塊病斑處分離出七株具病原性之鏈黴菌菌株，經形態、生理生化及分子生物學特徵鑑定皆與為Streptomyces scabies種的特徵相符；在生物防治應用上，則已証實由番石榴根圈分離之拮抗性枯草桿菌WG 6-14菌株，具顯著抑制此病原菌感染之能力。在接續計劃工作中，首先將由解析本省分離病原菌株之16S rDNA序列，以瞭解不同分離株與已知病原菌株間之親緣關係，期由而瞭解導致本病爆發可能之病原傳播途徑；另外就病原菌之致病性研究中將以攸關病徵表現thaxtomin A毒質為主要檢測標的，檢討毒質產生量與病原菌株毒力間的相關性，其中毒質之檢測除利用HPLC配合串連式質譜儀分析測試，並利用馬鈴薯圓盤與蘿蔔幼苗生物檢測法一併檢測其致病活性，此外基於病原檢測之需要，試驗中將利用專一性引子對選殖、解序thaxtomin A生合成關鍵基因tomA，並由而設計製備專一性探針以供檢防疫工作上病原菌株之檢測應用；就本病之防治管理，本年度計劃中將繼續利用溫室栽培馬鈴薯人工接種模式系統，繼續檢討拮抗性枯草桿菌WG 6-14於土壤及種薯人工接種病原菌情況下對病害發生之抑制效果，本計劃之最終目標在提供馬鈴薯栽培上有效管理本病發生感染之策略。
The proposed works will explore mainly the biological and pathogenic characteristics of the agent which caused the severe scab disease outbreaks on potato during the past 2 years in central and southern Taiwan, and the possibility of using probiotic/antagonistic Bacillus subtilis as biofungicide for the disease control. In our previous work, 7 Streptomyces spp. strains isolated from diseased lesions were shown to be pathogenic, and species characterization by morphological, physiological, biochemical and molecular characteristics indicated all of them close resemble that of Streptomyces scabies. And for the biological control of the disease, some preliminary greenhouse trials have indicated that the application of Bacillus subtilis var. amyloliquefaciens WG6-14- an antagonistic bacilli isolated from guava rhizosphere significantly reduced the infection of the scab bacteria. In the continued works, we intend to explore further by molecular characterization of the 16S rDNAs the phylogenetic relationships of the pathogenic strains prevailing in the field hopefully to shed some lights on the route of disease transmission. To understand better the biological chacteristics of these prevailing pathogen strains, the correlation of thaxtomin A toxin productivity and strain virulence will be examined. The molecular characteristics of the target toxin will be determined and elucidated by HPLC equipped with a triplequad mass/mass detector. Whereas the pathological effects will be determined by biological assay using potato discs and radish cotyledons as target system. As tomA gene has been shown to be one of the determinants of pathogenicity existing on the pathogen genome, the cloning and characterization of tomA from the tester strains will be also attempted. The possibility of using tomA specific fragment as specific probes for pathogenic strain detection and its usefulness in seed tuber quarantine application will be also explored. As for disease management, the effectiveness of B. subtilis var. amyloliquefaciens WG6-14 as biocontrol agent will be further explored by greenhouse trial where that the pathogen are artificially introduced by soil and as well by seed tuber inoculation. The ultimate goal of the project is to provide a feasible resolution for the new disease outbreak on potato cultivation.
|Appears in Collections:||動物科學系|
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