Mycotoxin profiles in the grain of Triticum monococcum, Triticum dicoccum and Triticum spelta after head infection with Fusarium culmorum

Mycotoxin profiles and plumpness of Tritordeum grain after artificial spike inoculation with Fusarium culmorum W.G. Smith

The responses to artificial spike inoculation with Fusarium culmorum were compared in 11 Tritordeum lines, two durum wheat cultivars and one naked barley cultivar. Inoculation of Tritordeum spikes led to a significant decrease in spike weight, kernel weight per spike, and kernel weight (by 18, 28, and 16 %, respectively). Durum wheat responded most strongly to inoculation, particularly with regard to spike weight and kernel weight per spike (decrease of 42 % and 53 %, respectively). Inoculation induced a significant increase in the total concentration of trichothecenes (9902 vs 558 μg/kg in non-inoculated control) and other Fusarium toxins (40,207 vs 3250 μg/kg in non-inoculated control) in Tritordeum grain. The content of three Alternaria toxins was not significantly modified by inoculation. The principal component analysis (PCA) of all fungal metabolites supported the discrimination of control and inoculated grain, and the results were used to divide the examined Tritordeum lines into two groups with different mycotoxin profiles. The first group (five lines) was more similar to naked barley, whereas the second group (six lines) showed greater similarity to durum wheat. The analyzed Tritordeum lines responded differently to inoculation, which suggests that lines with a low propensity to accumulate Fusarium toxins in grain can be selected from the existing gene pool. The study also demonstrated that Tritordeum grain accumulates significantly smaller amounts of mycotoxins than durum wheat grain.

Origin and characterization of cyclodepsipeptides: Comprehensive structural approaches with focus on mass spectrometry analysis of alkali-cationized molecular species

Cyclodepsipeptides (CDPs) represent a huge family of chemically and structurally diverse molecules with a wide ability for molecular interactions. CDPs are cyclic peptide-related natural products made up of both proteinogenic and nonproteinogenic amino acids linked by amide and ester bonds. The combined use of different analytical methods is required to accurately determine their integral structures including stereochemistry, thus allowing deeper insights into their often-intriguing bioactivities and their possible usefulness. Our goal is to present the various methods developed to accurately characterize CDPs. Presently, Marfey's method and NMR (nuclear magnetic resonance) are still considered the best for characterizing CDP configuration. Nevertheless, electrospray-high resolution tandem mass spectrometry (ESI-HRMS/MS) is of great value for efficiently resolving CDP's composition and sequences. For instance, recent data shows that the fragmentation of cationized CDPs (e.g., [M + Li]+ and [M + Na]+) leads to selective cleavage of ester bonds and specific cationized product ions (b series) useful to get unprecedented sequence information. Thus, after a brief presentation of their structure, biological functions, and biosynthesis, we also provide a historic overview of these various analytical approaches as well as their advantages and limitations with a special emphasis on the emergence of methods based on HRMS/MS through recent fundamental works and applications.

Linking Multi-Omics to Wheat Resistance Types to Fusarium Head Blight to Reveal the Underlying Mechanisms

Fusarium head blight (FHB) caused by Fusarium graminearum is a worldwide disease which has destructive effects on wheat production, resulting in severe yield reduction and quality deterioration, while FHB-infected wheat grains are toxic to people and animals due to accumulation of fungal toxins. Although impressive progress towards understanding host resistance has been achieved, our knowledge of the mechanism underlying host resistance is still quite limited due to the complexity of wheat-pathogen interactions. In recent years, disease epidemics, the resistance germplasms and components, the genetic mechanism of FHB, and disease management and control, etc., have been well reviewed. However, the resistance mechanism of FHB is quite complex with Type I, II to V resistances. In this review, we focus on the potential resistance mechanisms by linking different resistance types to multi-omics and emphasize the pathways or genes that may play significant roles in the different types of resistance. Deciphering the complicated mechanism of FHB resistance types in wheat at the integral levels based on multi-omics may help discover the genes or pathways that are critical for different FHB resistance, which could then be utilized and manipulated to improve FHB resistance in wheat breeding programs by using transgenic approaches, gene editing, or marker assisted selection strategies.

Genome-wide association study for deoxynivalenol production and aggressiveness in wheat and rye head blight by resequencing 92 isolates of Fusarium culmorum

Background

Fusarium culmorum is an important pathogen causing head blight of cereals in Europe. This disease is of worldwide importance leading to reduced yield, grain quality, and contamination by mycotoxins. These mycotoxins are harmful for livestock and humans; therefore, many countries have strict regulatory limits for raw materials and processed food. Extensive genetic diversity is described among field populations of F. culmorum isolates for aggressiveness and production of the trichothecene mycotoxin deoxynivalenol (DON). However, the causes for this quantitative variation are not clear, yet. We analyzed 92 isolates sampled from different field populations in Germany, Russia, and Syria together with an international collection for aggressiveness and DON production in replicated field experiments at two locations in two years with two hosts, wheat and rye. The 30x coverage whole-genome resequencing of all isolates resulted in the identification of 130,389 high quality single nucleotide polymorphisms (SNPs) that were used for the first genome-wide association study in this phytopathogenic fungus.

Results

In wheat, 20 and 27 SNPs were detected for aggressiveness and DON content, respectively, of which 10 overlapped. Additionally, two different SNPs were significantly associated with aggressiveness in rye that were among those SNPs being associated with DON production in wheat. Most of the SNPs explained only a small proportion of genotypic variance (p_G), however, four SNPs were associated with major quantitative trait loci (QTLs) with p_G ranging from 12 to 48%. The QTL with the highest p_G was involved in DON production and associated with a SNP most probably located within the Tri4 gene.

Conclusions

The diversity of 92 isolates of F. culmorum were captured using a heuristic approach. Key phenotypic traits, SNPs, and candidate genes underlying aggressiveness and DON production were identified. Clearly, many QTLs are responsible for aggressiveness and DON content in wheat, both traits following a quantitative inheritance. Several SNPs involved in DON metabolism, among them the Tri4 gene of the trichothecene pathway, were inferred as important source of variation in fungal aggressiveness. Using this information underlying the phenotypic variation will be of paramount importance in evaluating strategies for successful resistance breeding.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07931-5.

The Inhibitory Effect of Wheat Husks Addition on Aflatoxins Production by Aspergillus flavus in Liquid Culture With Various Wheat Compositions as Carbon Sources

Wheat may be infected by the aflatoxigenic mold Aspergillus flavus during pre- and post-harvest activities. Control strategies reported to manage aflatoxin contamination of wheat are expensive and require extensive testing to verify the absence of toxic secondary metabolites or newly formed compounds. The objective of this study was to develop an in vitro new control strategy based on assessing the influence of wheat husks on aflatoxin production by A. flavus in liquid culture. The results showed that aflatoxin production is significantly influenced by the existence of husks in the wheat forms used as carbon substrates according to the following order: full wheat grains < half-crushed wheat grains < wheat flour 82% < wheat flour 72%. By applying a fractional factorial design and a response surface methodology, maximum aflatoxin production (2.567 ng/mg) was predicted when wheat flour 72% (39 g/l) as a carbon source, yeast extract (5 g/l), and a 75-ml medium volume/250 ml flask were utilized. At this optimized condition, after addition of wheat husk extract, the growth and synthesis of aflatoxins of A. flavus were repressed by 74.85 and 98.72%, respectively. This finding paves the way to examine the antifungal potential of wheat husk constituents and to compare their efficacy with thyme, cinnamon, sweet basil, and coriander essential oils, which possess antimycotic activities. Accordingly, the wheat husk component SiO₂ showed the highest growth inhibition (67.04%) and reduction of A. flavus aflatoxins (82.67%). These results are comparable to those obtained from various examined antimycotic essential oils.

Spelt vs common wheat: potential advantages and benefits

This work gives a brief review of existing studies that compares spelt and modern wheat from various aspects of quality including technological, nutritional, functional and safety performance. Spelt shows acceptable breadmaking performances. It can be used for bread, cookie, cracker and pasta manufacture with some adaptations in processing. Regarding nutritional quality, spelt is very similar to wheat and represents richer source of selenium, folates, phytosterols and alkilresorcinols than modern wheats. From the aspect of food safety, spelt shows advantages as being a hulled wheat.

The Response of Selected Triticum spp. Genotypes with Different Ploidy Levels to Head Blight Caused by Fusarium culmorum (W.G.Smith) Sacc

Several cultivars and pure lines of Triticum monococcum, T. dicoccon, T. polonicum, T. spelta and T. aestivum were inoculated with Fusarium culmorum, the causal agent of Fusarium head blight in wheat. During the three-year study, the infection decreased the values of the analyzed yield components: spike weight (by 5.6% to 15.8%), number of kernels per spike (by 2.8% to 11.8%) and one kernel weight (by 8.4% to 10.7%). T. spelta was characterized by the weakest average response to infection. The grain from inoculated spikes contained significantly higher concentrations of deoxynivalenol (DON) and its 3-β-D-glucoside (D3G) than control grain. The D3G/DON ratio ranged from 11.4% to 21.4% in control grain and from 8.1% to 11.6% in inoculated grain. The lowest levels of mycotoxins were found in spelt, and the highest in T. polonicum lines and Kamut. PCA revealed that the grain of T. polonicum was characterized by an entirely different mycotoxin profile. The weakest response to F. culmorum infections was noted in T. spelta, and the strongest response in T. polonicum breeding lines and Kamut.