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Pathogenicity and phylogeny of Fusarium oxysporum causing cucurbit wilting in Taiwan

Ching-Chen Chung: National Chung Hsing University

<div>Cucurbitaceae is one of important vegetable and widely distributed over the word. Several important diseases are common during growth season, such as Fusarium wilt, downy meildew and anthracnoe. Among these diseases, the Fusarium wilt caused by <em>F. oxysproum</em> (<em>Fo</em>) is most important disease in cucubit production area. Currently, more than 150 formae speciales have been recoded throughout the world. Although formae speciales show the pathogenic specificity on their host, the cross-pathogenicity has been found in different formae speciales. Previous studies domonstrated that certain formae speciales of <em>F. oxysporum</em> causing cucurbit wilt could show cross-pathogencity between different cucubit. In this study, the <em>F. oxysproum </em>obtained from cucumber, bitter gourd and loofah were used to examine the cross-pathogenicty between the three cucurbits and carried out their phylogeny. The results indicated that<em> F. oxysproum</em> isolates from cucubmer and bitter gourd could infect loofah and <em>F. oxysporum</em> isolates from loofah could infect cucumber at 20℃ based on root dipping method. In addition, some of loofah plants could be infected by<em> F. oxysporum</em> isolates from bitter gourd at 28℃ with root dipping method. For phylogeny analysis, the <em>F. oxysporum</em> isolates from three cucurbits did not associate with host specificity based on <em>IGS</em> and <em>EF-1</em><em>α</em> sequences. However, the nucleotides of secreted in the xylem (<em>SIX</em>) protein 6 could separe the<em> F. oxysporum</em> isolates from three cucurbits.</div>