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Identification of roselle wilt disease and development of control strategies
roselle wilt disease,Fusarium solani,Bacillus amyloliquefaciens,Streptomyces misionensis,pyraclostrobin,biological control,chemical control,
|Publication Year :||2021|
|Abstract:||在台灣，近年之洛神葵田間病害調查報導，洛神葵萎凋病普遍發生，但其肇因仍未知。洛神葵萎凋病之病株莖基部呈現褐化且輕微縊縮之病徵，並可觀察到白色之氣生菌絲，縱切面維管束偶有褐化現象，多數則呈髓部腐爛之徵狀，鏡檢後亦可發現典型的鐮孢菌(Fusarium spp.)之大、小分生孢子，顯示此病害可能由鐮孢菌造成。本研究蒐集了二批來自台東縣六個不同種植地的洛神葵萎凋病樣本，經由ITS及16S rDNA之序列分析後，分離得之64株菌株包含真菌、卵菌以及細菌。利用柯霍氏法則測試這些分離到的菌株後發現，Fusarium solani K2 (FsK2)菌株會造成洛神葵植株萎凋及髓部腐爛且與田間相似之病徵。進一步利用掃描式電子顯微鏡觀察，於接種後發病之植株，FsK2之菌絲會纏據於莖基部表面，且偶可在腐爛的髓部觀察到小分生孢子與似侵入之構造。此研究為首次證明在台灣，茄鐮孢菌可造成洛神葵萎凋病的發生。此外，洛神葵種子帶菌檢測結果顯示沒有由種子攜帶F. solani的情形，此病害由種子傳播之機率較低。再者，我們發現Bacillus amyloliquefaciens Ba01、Streptomyces misionensis KHY26和殺菌劑百克敏(pyraclostrobin)可以防治洛神葵萎凋病，在盆栽試驗中分別達到76.9%、96.1%和96.1%的防治率，此方面可作為後續生物防治與化學防治之策略。|
A roselle (Hibiscus sabdariffa L.) disease survey conducted recently in Taiwan reported that roselle wilt disease occurs widely; however, the causal agent is unknown. The stems of wilted roselle were browned, slightly constricted, and showed white aerial hyphae. Rotted pith was found in the vertically dissected stem base and macroconidia and microconidia typical of the Fusarium species were observed under a microscope indicating that roselle wilt might be caused by Fusarium spp. In this study, we isolated 64 strains from wilted plants grown in six roselle fields in Taitung county, Taiwan. After ITS and 16S rDNA sequence analysis, the 64 strains were identified as different species of fungi, oomycetes or bacteria. Koch’s postulates were used to evaluate the pathogenicity of these strains, among which we found that Fusarium solani K2 (FsK2) can cause wilting and rotted pith on roselles similar to those observed in the fields. Using a scanning electron microscope, we found that mycelia of FsK2 can colonize on roots, while microconidia and penetration-like structures were sometimes found in the rot pith. This is the first demonstration that F. solani can cause roselle wilt in Taiwan. On the other hand, roselle seeds were tested and no seeds were contaminated by F. solani, indicating that the disease may not be seed-borne. Furthermore, we found that Bacillus amyloliquefaciens Ba01, Streptomyces misionensis KHY26, and fungicide pyraclostrobin can control roselle wilt with a 76.9%, 96.1%, and 96.1% control rate, respectively, and therefore might serve as potential biological and chemical control strategies against roselle wilt disease in the future.
|Appears in Collections:||植物病理與微生物學系|
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