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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. Generally, rice leaf media more effectively increased conidiation than panicle media, and certain non-filtered tissue media were better than their filtered counterparts. Among the tested media, the Indica rice leaf medium with 0.06 g/ml of Wanxian 98 leaf was most efficient for inducing conidiation, and it was also usable for conidiation-defective isolates. Although the conidia induced in rice tissue media were smaller, they were able to germinate on potato sucrose agar medium and infect rice normally. This method provides a foundation for the production of conidia in U. virens that will be widely applied in the pathogenicity testing as well as in genetic analyses for false smut resistance in rice cultivars.

Bax inhibitor-1 (BI-1), an evolutionarily conserved protein, is a suppressor of cell death induced by the proapoptotic protein Bax and is involved in the response to biotic and abiotic stress in animals, plants and yeast. Rice false smut caused by Ustilaginoidea virens is one of the destructive rice diseases worldwide. Although BI-1 proteins are widely distributed across filamentous fungi, few of them are functionally characterized. In this study, we identified a BI-1 protein in U. virens, UvBI-1, which contains a predicted Bax inhibitor-1-like family domain and could suppress the cell death induced by Bax. By co-transformation of the CRISPR/Cas9 construct along with donor DNA fragment containing the hygromycin resistance gene, we successfully generated Uvbi-1 deletion mutants. The UvBI-1 deletion showed an increase in mycelia vegetative growth and conidiation, suggesting this gene acts as a negative regulator of the growth and conidiation. In addition, the Uvbi-1 mutants exhibited higher sensitivity to osmotic and salt stress, hydrogen peroxide stress, and cell wall or membrane stress than the wild-type strain. Furthermore, UvBI-1 deletion was found to cause increased production of secondary metabolites and loss of pathogenicity of U. virens. Taken together, our results demonstrate that UvBI-1 plays a negative role in mycelial growth and conidiation, and is critical for stress tolerance, cell wall integrity, secondary metabolites production and pathogenicity of U. virens. Therefore, this study provides new evidence on the conserved function of BI-1 among fungal organisms and other species.

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.

As the projection matrix is only generated in the initial stage and kept constant in subsequent processing, so when the object is occluded or its appearance changes, this will result in drifting or tracking lost. To address this problem, this paper proposes a real-time compressive tracking algorithm based on online feature selection. First, the feature pools are constructed. Then, features with high confidence score are selected from the feature pool by a confidence evaluation strategy. These discriminating features and their corresponding confidences are integrated to construct a classifier. Finally, tracking processing is carried on by the classifier. Tracking performance of our algorithm compares with that of the original algorithm on several public testing video sequences. Our algorithm improves on the tracking accuracy and robustness; furthermore, the processing speed is approximately 25 frames per second. It meets the requirements of real-time tracking.

In this paper, the research purpose is how to measure the errors of the gun barrel pointing to the target for the towed anti-aircraft guns. The paper proposes an image processing algorithm based on the local entropy to solve the problem of the pointing error. First, fix the CCD image acquisition device on the gun barrel and ensure that its optical axis be parallel to the barrel axis. Second, the target video images are captured during the target tracking process and are processed with the algorithm based on the local entropy, and so the errors of the CCD optical axis pointing to the target can be obtained. At last, by the parallax correction, the errors of the gun barrel pointing to the target can be gotten. After the field test, the algorithm's effectiveness and practicality for this device have been validated.