Rice false smut, caused by the ascomycete Ustilaginoidea virens, is a serious disease of rice worldwide. Conidia are very important infectious propagules of U. virens, but the ability of pathogenic isolates to produce conidia frequently decreases in culture, which influences pathogenicity testing. Here, we developed tissue media with rice leaves or panicles that stimulate conidiation of U. virens. Among the tested media, 0.10 g/ml panicle medium was most efficient for conidiation. Whereas, some rice leaf media more effectively increased conidiation than panicle media except 0.10 g/ml panicle medium, and certain non-filtered tissue media were better than their filtered counterparts. Although the conidia induced in rice tissue media were smaller, they were able to germinate on potato sucrose agar medium and infect rice normally. The rice tissue medium is also workable in inducing conidia for conidiation-defective isolates. This method provides a foundation for the production of conidia by U. virens that will be widely applicable in pathogenicity testing as well as in genetic analyses for false smut resistance in rice cultivars.
Rice false smut, caused by Ustilaginoidea virens, is one of the most destructive diseases in major world rice-producing regions. Basic leucine zipper (bZIP) proteins, which belong to an evolutionarily conserved transcription factor family and play critical roles in various biological processes in eukaryotes, have been previously identified in U. virens; however, their functions still need to be further elucidated. Therefore, we aimed to analyze the biological roles of UvbZIP6, a member of the bZIP family in U. virens. In this study, we found that UvbZIP6 was highly up-regulated at 7 days post-inoculation. Deletion of UvbZIP6 in U. virens resulted in an increase in fungal growth and sensitivity to Congo red and calcofluor white, whereas a decrease in sensitivity to hyperosmotic, oxidative, and sodium dodecyl sulfate stresses. Conidiation capacity was reduced in UvbZIP6-knockout mutants, but conidial morphology and germination were not affected. Although UvbZIP6-knockout mutants caused infection in rice plants, they could not form false smut balls. Our study indicates that UvbZIP6 is required for fungal growth, conidiation, stress response, and false smut ball formation of U. virens.
27Rice false smut, caused by the ascomycete Ustilaginoidea virens, is a serious disease 28 of rice worldwide. Conidia are very important infectious propagules of U. virens, but 29 the ability of pathogenic isolates to produce conidia frequently decreases in culture, 30 which influences pathogenicity testing. Here, we developed tissue media with rice 31 leaves or panicles that stimulate conidiation of U. virens. Generally, rice leaf media 32 more effectively increased conidiation than panicle media, and certain non-filtered 33 tissue media were better than their filtered counterparts. Among the tested media, the 34 Indica rice leaf medium with 0.06 g/ml of Wanxian 98 leaf was most efficient for 35 inducing conidiation, and it was also usable for conidiation-defective isolates. 36 Although the conidia induced in rice tissue media were smaller, they were able to 37 germinate on potato sucrose agar medium and infect rice normally. This method 38 provides a foundation for the production of conidia in U. virens that will be widely 39 applied in the pathogenicity testing as well as in genetic analyses for false smut 40 resistance in rice cultivars. 41 42 43 44 45 46 47 48 49 50 52 Rice false smut (RFS), caused by the ascomycete Ustilaginoidea virens, has 53
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.