Sofie Landschoot

Natural occurrence of mycotoxins and their masked forms in food and feed products

A total of 174 cereal-based food products, 67 compound feeds and 19 feed raw materials were analysed for the occurrence of deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, zearalenone, α-zearalenol, β-zearalenol, and their respective masked forms, including deoxynivalenol-3-glucoside, zearalenone-4-glucoside, α-zearalenol-4-glucoside, β-zearalenol-4-glucoside and zearalenone-4-sulfate. Fibre-enriched bread, bran-enriched bread, cornflakes, popcorn and oatmeal were collected in Belgian supermarkets from April 2010 to October 2011. All food samples analysed were contaminated with an average of 2 to 6 mycotoxins, including 1 to 3 masked forms. Feed raw materials that were used in the analysed compound feeds were collected by the manufacturer. Feed raw materials included were beet pulp, sunflower seed meal, soy bean, soy peel, oats, barley, maize germs, maize gluten feed, maize, wheat gluten feed, wheat bran pellets, wheat bran and wheat. Beet pulp, sunflower seed meal, soy bean and soy peel w...

Combining linkage and association mapping identifies RECEPTOR-LIKE PROTEIN KINASE1 as an essential Arabidopsis shoot regeneration gene

Significance The regeneration of entire plants from explants is an important step in plant production and plant transformation protocols. Despite recent advances in the knowledge on the molecular basis of regeneration, many aspects of the process and the causes of regeneration recalcitrance are still poorly understood. We combined linkage with association mapping to find genes underlying the natural variation of shoot regeneration in Arabidopsis. With this approach, we identified and confirmed the involvement of RECEPTOR-LIKE PROTEIN KINASE1 as a previously unknown determinant of shoot regeneration. Because this gene is implicated in abscisic acid signaling, it seems that this hormone might be an important player in this developmental process. De novo shoot organogenesis (i.e., the regeneration of shoots on nonmeristematic tissue) is widely applied in plant biotechnology. However, the capacity to regenerate shoots varies highly among plant species and cultivars, and the factors underlying it are still poorly understood. Here, we evaluated the shoot regeneration capacity of 88 Arabidopsis thaliana accessions and found that the process is blocked at different stages in different accessions. We show that the variation in regeneration capacity between the Arabidopsis accessions Nok-3 and Ga-0 is determined by five quantitative trait loci (QTL): REG-1 to REG-5. Fine mapping by local association analysis identified RECEPTOR-LIKE PROTEIN KINASE1 (RPK1), an abscisic acid-related receptor, as the most likely gene underlying REG-1, which was confirmed by quantitative failure of an RPK1 mutation to complement the high and low REG-1 QTL alleles. The importance of RPK1 in regeneration was further corroborated by mutant and expression analysis. Altogether, our results show that association mapping combined with linkage mapping is a powerful method to discover important genes implicated in a biological process as complex as shoot regeneration.

The compositional mosaic of Fusarium species and their mycotoxins in unprocessed cereals, food and feed products in Belgium

Global food safety depends on continuous monitoring of food contaminants such as mycotoxins in cereals and cereal-derived products. Here, we combine this type of investigation with quantitative occurrence data on Fusarium infestation of these products in extensive correlation studies. Finally, this contributes to a thorough understanding of the presence, origin and physiology of Fusarium Head Blight (FHB) related mycotoxins and the correlations within their ranks. Two hundred and thirty-seven samples were analyzed from diverse cereal matrices, representing the most important stages of the cereal food and feed chain in Belgium. Food, feed and non-processed field samples were investigated, with a strong emphasis on whole-grain food products. Two approaches were pursued to estimate the full scope of FHB and its repercussions: UPLC-MS/MS was applied to detect twelve different mycotoxins, and Q-PCR was used to measure the presence of ten Fusarium species. We found that different matrices have different characteristic contamination profiles, and extensive correlation studies identified certain mycotoxins for future assessment (e.g. moniliformin produced by the Fusarium avenaceum/Fusarium tricinctum species group). The investigated harvest year of 2012 yielded many non-processed field materials containing elevated levels of deoxynivalenol (DON), while even in a so-called DON-year less prevalent toxins such as T-2 and HT-2 might be considered problematic due to their consistent co-occurrence with related mycotoxins. Our data illustrate complex interactions between the many Fusarium species that are responsible for FHB and their mycotoxins. Correlation studies demonstrate that consistent co-occurrence of mycotoxins is not to be neglected, and pinpoint issues for future surveillance and legislation.

Toward a Reliable Evaluation of Forecasting Systems for Plant Diseases: A Case Study Using Fusarium Head Blight of Wheat

Despite great efforts to forecast plant diseases, many of the existing systems often fall short in providing farmers with accurate predictions. One of the main problems arises from the existence of year and location effects, so that more advanced procedures are required for evaluating existing systems in an unbiased manner. This paper illustrates the case of Fusarium head blight of winter wheat in Belgium. We present a new cross-validation strategy that enables the evaluation of the predictive performance of a forecasting system for years and locations that are different from the years and locations on which the forecast was developed. Four different cross-validation strategies and five regression techniques are used. The results demonstrated that traditional evaluation strategies are too optimistic in their predictions, whereas the cross-year cross-location validation strategy yielded more realistic outcomes. Using this procedure, the mean squared error increased and the coefficient of determination decreased in predicting disease severity and deoxynivalenol content, suggesting that existing evaluation strategies may generate a substantial optimistic bias. The strongest discrepancies between the cross-validation strategies were observed for multiple linear regression models.

Occurrence and within field variability of Fusarium mycotoxins and their masked forms in maize crops in Belgium

Maize ear rot caused by several Fusarium species is an important fungal disease. Apart from yield losses, ear rot fungi can produce mycotoxins and masked forms in infected grains. Masked mycotoxins have received increased attention in view of their bioavailability and potential toxicity in animals and humans, but their presence and relevance in the field still remain undisclosed. To get a better insight, the present study assessed the presence of various Fusarium parent and masked mycotoxins, i.e. deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, deoxynivalenol-3-glucoside, zearalenone, α-zearalenol, β-zearalenol, zearalenone-14-glucoside, zearalenone-14-sulfate, α-zearalenol-14-glucoside, β-zearalenol-14-glucoside, T-2 and HT-2 toxin, in various commercial maize varieties grown under natural infection conditions in Flanders, Belgium. The results showed that the maize varieties were co-contaminated with both parent and masked mycotoxins. Moreover, a positive correlation between these forms ...

Impact of Fungicide Timing on the Composition of the Fusarium Head Blight Disease Complex and the Presence of Deoxynivalenol (DON) in Wheat

Kris Audenaert1,2, Sofie Landschoot1,2, Adriaan Vanheule1,2, Willem Waegeman3, Bernard De Baets3 and Geert Haesaert1,2 1Associated Faculty of Applied Bioscience Engineering, Ghent University College, Ghent 2Laboratory of Phytopathology, Faculty of Bioscience Engineering, Ghent University, Ghent 3KERMIT, Department of Mathematical Modelling, Statistics and Bioinformatics, Ghent University, Ghent Belgium

Biotic stresses in the anthropogenic hybrid triticale (×Triticosecale Wittmack): current knowledge and breeding challenges

Triticale (×Triticosecale Wittmack) is the intergeneric hybrid derived by crossing wheat (Triticum spp.) and rye (Secale spp.). Consequently, the same spectrum of fungal diseases occurring on the parent crops can impede optimal triticale production. With the expansion of the triticale growing area, the scientific interest into these fungal pathogens has gained momentum. This review considers the major fungal diseases occurring on triticale: powdery mildew, rust diseases, and Fusarium head blight and highlights breeding strategies or opportunities to control these pathogens. Although there are several models to explain the emergence of pathogens in newly introduced crops, for powdery mildew on triticale, it is accepted that it emerged through a host range expansion of wheat powdery mildew. Moreover, this host range expansion of wheat powdery mildew occurred recently, multiple times and at different locations in Europe. For rust diseases and Fusarium, evidence for such an abrupt host shift is rather thin and suggests an evolution in disease incidence and virulence confluent with evolving management practices, variable seasons, mutations, recombination and variety selection. In order to overcome these fungal pathogens in triticale, plant breeding is a powerful tool. Despite the multiple parallelisms between fungal diseases in triticale and wheat, the narrow genetic background, partially due to the narrow genetic background of the parental crops, is a serious issue in triticale breeding. It remains a challenge for future breeding strategies to broaden the genetic background of new varieties that are being developed, through introgression and deployment of new sources of disease resistance. Especially, quantitative and multi-pathogen sources of resistance have to be considered. In this way, triticale can retain its position as important low input farming cereal crop.

Deoxynivalenol content in wheat dust versus wheat grain: a comparative study

The present study, set up in the growing season 2011-2012, was designed to obtain quantitative data on the occurrence of deoxynivalenol in wheat grain and the corresponding wheat dust. The field experiment consisted of a complete randomised block design with five wheat varieties sown on a field on which maize was grown in the previous season. The impact of the tillage method and the influence of the wheat variety resistance on the deoxynivalenol content of wheat and wheat dust were investigated. The accumulation of deoxynivalenol in wheat dust was confirmed and a sigmoidal relationship between the deoxynivalenol content in wheat dust versus wheat grain was determined. Deoxynivalenol reduction was obtained by ploughing and by sowing moderately resistant wheat varieties. As wheat dust provides equal results and solves the problem of heterogeneity during sampling of conventional wheat matrix, the sampling of wheat dust can be considered as a promising alternative.

Genetic and toxigenic variability within Aspergillus flavus population isolated from maize in two diverse environments in Kenya

Aspergillus flavus is the main producer of carcinogenic aflatoxins in agricultural commodities such as maize. This fungus occurs naturally on crops, and produces aflatoxins when environmental conditions are favorable. The aim of this study is to analyse the genetic variability among 109 A. flavus isolates previously recovered from maize sampled from a known aflatoxin-hotspot (Eastern region, Kenya) and the major maize-growing area in the Rift Valley (Kenya), and to determine their toxigenic potential. DNA analyses of internal transcribed spacer (ITS) regions of ribosomal DNA, partial β-tubulin gene (benA) and calmodulin gene (CaM) sequences were used. The strains were further analyzed for the presence of four aflatoxin-biosynthesis genes in relation to their capability to produce aflatoxins and other metabolites, targeting the regulatory gene aflR and the structural genes aflP, aflD, and aflQ. In addition, the metabolic profile of the fungal strains was unraveled using state-of-the-art LC-MS/MS instrumentation. The three gene-sequence data grouped the isolates into two major clades, A. minisclerotigenes and A. flavus. A. minisclerotigenes was most prevalent in Eastern Kenya, while A. flavus was common in both regions. A. parasiticus was represented by a single isolate collected from Rift Valley. Diversity existed within the A. flavus population, which formed several subclades. An inconsistency in identification of some isolates using the three markers was observed. The calmodulin gene sequences showed wider variation of polymorphisms. The aflatoxin production pattern was not consistent with the presence of aflatoxigenic genes, suggesting an inability of the primers to always detect the genes or presence of genetic mutations. Significant variation was observed in toxin profiles of the isolates. This is the first time that a profound metabolic profiling of A. flavus isolates was done in Kenya. Positive associations were evident for some metabolites, while for others no associations were found and for a few metabolite-pairs negative associations were seen. Additionally, the growth medium influenced the mycotoxin metabolite production. These results confirm the wide variation that exists among the group A. flavus and the need for more insight in clustering the group.

Impact of Crop Husbandry Practices and Environmental Conditions on Wheat Composition and Quality: A Review

The increasing interest in the production of bread wheat ( Triticum aestivum L.) with specific quality traits requires a shift from the current breeding goal, being yield, to improved compositional and, consequently, functional traits. Since wheat is a key food crop, this must be attained while maintaining or even further increasing yield. Furthermore, as compositional requirements for specific applications are not well-defined, both protein and gluten content as well as the enzymatic activity remain most important. Given that these traits are majorly impacted by both genotype and environment, it is very complex to predict and ultimately control them. Different strategies, such as applying optimized agronomic practices, can temper these uncontrollable determinants which are equally important to steer wheat quality. As current research on their contribution to specific traits is highly fragmented, this report provides a comprehensive review of the influence of crop husbandry and environmental conditions on wheat yield and composition.