No abstract

Marine fungi produce various secondary metabolites with unique chemical structures and diverse biological activities. In the continuing search for new antifungal agents from fungi isolated from marine environments, the culture filtrate of a fungus Aspergillus tabacinus SFC20160407-M11 exhibited the potential to control plant diseases caused by fungi. From the culture filtrate of A. tabacinus SFC20160407-M11, a total of seven compounds were isolated and identified by activity-guided column chromatography and spectroscopic analysis: violaceol I ( 1 ), violaceol II ( 2 ), diorcinol ( 3 ), versinol ( 4 ), orcinol ( 5 ), orsellinic acid ( 6 ), and sydowiol C ( 7 ). Based on in vitro bioassays against 17 plant pathogenic fungi and bacteria, violaceols and diorcinol ( 1 – 3 ) showed a broad spectrum of antimicrobial activity with minimum inhibitory concentration values in the range of 6.3–200 μg mL –1 . These compounds also effectively reduced the development of rice blast, tomato late blight, and pepper anthracnose caused by plant pathogenic fungi in a dose-dependent manner. Our results suggest that A. tabacinus SFC20160407-M11 and its phenyl ether compounds could be used for developing new antimicrobial agents to protect crops from plant pathogens.

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Land use maps specifying up-to-date acreage information on maize (Zea mays L.) cropping patterns are required by many stakeholders in Vietnam. Government statistics, however, lag behind by one year, and the official land use maps are only updated at 5-year intervals. The aim of this study was to apply the Savitzky–Golay algorithm to reconstruct noisy Enhanced Vegetation Index (EVI) time series (2003–2018) from Terra Moderate Resolution Imaging Spectroradiometer (MODIS) Vegetation Indices (MOD13Q1) to allow timely detection of changes in maize crop phenology, and then to employ a linear kernel Support Vector Machine (SVM) classifier on the reconstructed EVI time series to prepare the present-day maize cropping pattern map of Dak Lak province of Vietnam. The method was able to specify the spatial extent of areas cropped to maize with an overall map accuracy of 79% and could also differentiate the areas cropped to maize just once versus twice annually. The by-district mapped maize acreage shows a good agreement with the official governmental data, with a 0.93 correlation coefficient (r) and a root mean square deviation (RMSD) of 1624 ha.