Biology subjects

Krska, R.

Publications and source records attributed to Krska, R..

3 recordsLinked to original sources

bioRxiv2025

Culmorin inhibits detoxification of the mycotoxin deoxynivalenol by plant UDP-glucosyltransferases

The Fusarium metabolite culmorin (CUL) frequently co-occurs with the mycotoxin deoxynivalenol (DON) on cereals. While DON is recognized as a major Fusarium virulence factor on plants, the function of CUL is still unclear. Herein, we show that CUL-deficient F. graminearum mutants created by CLM1 deletion are less aggressive on wheat than the wild-type, accompanied by increased DON-3-glucoside/DON ratios in infected wheat ears. In root elongation assays with wheat and Brachypodium distachyon, CUL had no effect alone but significantly increased the toxicity of DON. Analysis of DON/CUL-treated roots further indicated that both wheat and B. distachyon are able to glucosylate CUL and that its presence impedes DON-glucosylation in both species. We identified two B. distachyon UDP-glucosyltransferases (UGT) able to glucosylate CUL and further investigated the effect of CUL on the kinetics of validated DON-glucosylating plant UGTs (BdUGT5g03300, HvUGT13248, OsUGT79). This suggested that CUL inhibits DON-glucosylation either by serving as competitive substrate with DON or by unproductive binding. Especially BdUGT5g03300 was strongly inhibited by CUL and even its glucosides. Our results indicate that CUL contributes to Fusarium virulence by weakening plant-defenses related to UGT-catalyzed DON-detoxification. As even CUL-glucosides are potentially inhibitory to UGTs, this implies a complex synergy of CUL with DON. HighlightWe present biochemical evidence that the Fusarium metabolite culmorin contributes to Fusarium virulence on plants by suppressing detoxification of the virulence factor deoxynivalenol by glucosyltransferases.

biochemistry↗

bioRxiv2025

A portable 3D-printed near-infrared spectrometer to screen maize for deoxynivalenol and zearalenone contamination

Mycotoxins are toxic metabolites found in grains and cereals, posing a severe potential risk to human and animal health and significantly disrupting animal production, particularly in industries like pig farming. Current laboratory methods for mycotoxin analysis are expensive and time-intensive, creating a need for faster, more accessible solutions. This study set out to address this challenge by developing a portable spectrometer prototype based on the near-infrared (NIR) region and designing a chemometric model to classify ground maize as either non-compliant (NC) or compliant (C) for zearalenone (ZON) and deoxynivalenol (DON). A total of 259 naturally contaminated maize samples, collected over two years from diverse European regions, were analyzed using both liquid chromatography-tandem mass spectrometry (LC-MS/MS) and the prototype device. Spectral data were preprocessed using the first derivative, and a partial least squares discriminant analysis (PLS-DA) model was developed to classify ZON and DON levels into NC and C categories. Thresholds of 100 {micro}g/kg for ZON and 500 {micro}g/kg for DON were used to define compliance. The PLS-DA model showed good performance for ZON, achieving a classification accuracy of 86.3%. However, for DON classification a rather limited accuracy of 66.75% was achieved. While the DON model could identify NC samples it struggled with C samples. Despite these challenges, the results highlight the potential of a portable NIR spectrometer, combined with straightforward preprocessing and PLS-DA modeling, as a rapid, cost-effective screening tool for detecting mycotoxins in maize. The presented approach could significantly simplify mycotoxin monitoring, offering a practical solution to safeguard public health and enhance agricultural productivity.

pharmacology and toxicology↗

bioRxiv2024

Fusarium graminearum copper amine-oxidases redundantly increase virulence by converting tryptamine from hydrolyzed plant defense compounds into auxin

Plant pathogenic fungi have evolved different strategies to interfere with plant defense mechanisms. The well described fungal plant pathogen Fusarium graminearum is not only able to produce trichothecene toxins like deoxynivalenol, but also the plant hormone auxin. Highly elevated levels of auxin and auxin derivatives such as IAA-glucoside or IAA amino-acid conjugates were observed in wheat cultivar Apogee infected with F. graminearum. We report that F. graminearum is able to cleave tryptamine-derived hydroxycinnamic acid amides, e.g. the defense compound coumaroyl-tryptamine. In this study we investigated copper amine-oxidases, candidate genes for auxin biosynthesis converting tryptamine into the IAA precursor indole-3-acetyldehyde. After consecutive knock outs of all seven copper amine oxidases the resulting septuple knock out strain had strongly reduced ability to produce auxin. Virulence of the septuple mutant was significantly impaired while DON production in planta was comparable to the wild type. We conclude that F. graminearum, often presumed to be a simple nectrotroph, has a biotrophic phase and is able to employ plant defense compounds by converting them into defense suppressing auxin.

molecular biology↗