Abstract: The possibility of using hyperspectral imaging (HSI) techniques to classify different types of wheat kernels, vitreous, yellow berry and Fusarium-damaged, was investigated. Conventional optical techniques adopted by industry for wheat grain sorting usually have too high misclassification errors. Reflectance spectra of selected wheat kernels of the three types were acquired by a laboratory device equipped with an HSI system working in near infrared field (1000-1700 nm). The hypercubes were analysed applying different chemometric techniques, such as principal component analysis (PCA) for explorative purposes, partial least squares discriminant analysis (PLS-DA) for classification of the three wheat types and interval PLS-DA (iPLS-DA) for the selection of a reduced set of effective wavelength intervals. The study demonstrated that good classification results were obtained not only considering the entire investigated wavelength range, but also selecting only three narrow intervals of four wavelengths (1209-1230 nm, 1489-1510 nm and 1601-1622 nm) out of 121. The procedures developed could be utilised at industrial level for quality control purposes or for the definition of innovative sorting logics for wheat kernels after an extensive classification campaign, both at laboratory and industrial level, applied to a large wheat sample sets.
Abstract: Fusarium head blight (FHB) caused by several Fusarium species is one of the most serious diseases affecting wheat throughout the world. The in vitro production of the toxins deoxynivalenol, zearalenone fumonisin, T-2, and HT-2 was quantitvely evaluated in 8 different isolates of Fusarium species collected from feed samples. It was possible to detect zearalenone and the other mycotoxins in 100% and 50% of the isolates, respectively. In the present study, loop-mediated isothermal amplification method (LAMP) was designed for diagnosing Fusarium garmanirum infections and testing against feed samples, infested samples and pure cultures. The LAMP amplicon was directly visualized in the reaction tubes by the naked eye following the addition of calcein fluorescence. The LAMP products appeared as DNA marker pattern, with many bands of different sizes from 145 base pairs up to the loading well. Loop-LAMP procedure was used to detect genomic DNA of F. graminearum in fungal pure culture and in contaminated feed samples. In the future, this assay will support plant quarantine programs in Saudi Arabia and Gulf Cooperation Council states, to prevent the introduction of foreign FHB species.
Abstract: A comparison between two VIS-NIR spectral based systems performed in laboratory vs. in-field for the early detection of Fusarium head blight infection in two cultivars of durum wheat (Creso and Simeto) was carried out. The VIS-NIR spectrophotometric data were analysed with multivariate statistical tools. For both, laboratory and in-field experiments two analytical conditions were tested for two cultivars: diseased plants (artificial infection without fungicide treatment) and healthy plants (treatment with Folicur SE). Spectral measurements were performed at the different sampling times 6, 8, 12 and 15 d after artificial infection which correspond to the following Zadoks' scale growth stages: GS70, GS71, GS73 and GS75. The infection visible onset (VO) was then evaluated by an expert at the soft dough growth stage GS85. Since the growth stages revealed a great influence on spectral reflectance data, separated PLSDA models were adopted to differentiate diseased and healthy plants at the different sampling times. Using the Euclidean distance matrix cladogram results for the laboratory, three models were used considering spectral data from GS70, GS71+GS73, GS75, while for in-field data from GS70+GS71 and GS73+GS75. In the laboratory good performance of classification (86%) was observed at GS71+GS73 i.e., only 8-10 days after the infection. The in-field measurement showed a lower percentage of correct classification at the same growth stages. Finally the VIS-NIR spectral analysis could facilitate detection of Fusarium disease anticipating visual assessment.
Abstract: Fusarium wilt (Panama disease), caused by the fungus Fusarium oxysporum f. sp. cubense race 4 (Foc race 4), is one of the most destructive diseases affecting banana (Musa). Early and accurate detection of Foc race 4 is essential to protect the banana industry. We developed a novel and highly specific loop-mediated isothermal amplification (LAMP) assay for the detection of Foc race 4 based on a SCAR marker sequence. The detection limit for this assay was 10 fg per 25 µl reaction in pure culture and DNA amplification was completed within 60 min. The assays detected 69 different isolates of Foc race 4 from geographically distinct counties in China, and no cross-reaction was observed with other fungal pathogens. When 26 infected and eight healthy looking but infested banana samples naturally from different fields were examined, the detection rate of LAMP was 100%. The LAMP assay developed in this study was simple, fast, sensitive, and specific, and can be used in the field to detect Foc race 4 in infected banana plant tissue in resource-poor settings.
Abstract: The Fusarium genus causes devastating plant diseases worldwide, in which Fusarium oxysporum is the most serious crop pathogen. Disease monitoring is the basis of integrated pest management of any disease. The lack of rapid, accurate, and reliable device to detect and identify plant pathogens is one of the main limitations in integrated disease management. This study describes an efficient and quantifiable diagnosis method for the specific detection of F. oxysporum f. sp. cubense (Foc) race 4 in field-infected banana. With the optimized PCR parameters using the SCAR (sequence characterized amplified region) primers FocSc-1/FocSc-2 and a real-time PCR strategy, the developed method showed high reproducibility and was very sensitive to detect extremely low quantities of Foc genomic DNA (gDNA). We also found that Foc gDNA in severely symptomatic banana pseudostems and leaves were 6946-fold and 26.69-fold more than in those of mild-symptomatic banana, respectively.
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