Plant Protection News (Vestnik Zashchity Rasteniy)

Analysis of fungal and mycotoxin contamination of winter wheat grain grown in Krasnodarskiy Krai in 2023

E. P. Arabina — 2024-11-25

Using quantitative PCR (qPCR) and high-performance liquid chromatography with tandem mass spectrometry (HPLC MS/MS) ubiquitous presence of Fusarium and Alternaria fungi and their mycotoxins was detected in winter wheat grain grown in Krasnodarskiy Krai in 2023. All samples contained DNA of Fusarium producing trichothecene mycotoxins (Tri-Fusarium) in the range of 244–23537 pg/µg. DNA of Fusarium producing fumonisins was detected in 35 % of grain samples at 27–923 pg/µg. All samples contained Alternaria sect. Alternaria and sect. Infectoriae DNA at average levels of 3630±144 and 6814±214 pg/µg, respectively. Of the 36 analyzed mycotoxins, 17 metabolites were found in the grain samples: from 3 to 11 mycotoxins in each sample. Among Fusarium mycotoxins, most common were deoxynivalenol (DON) (in 79 % of samples), deoxynivalenol-3-glucoside (50 %), HT-2 toxin (47 %), and beauvericin (70 %). In two samples (6 % of the total), the maximum permissible DON concentration was exceeded by 2–3 times. A significant positive correlation between Tri-Fusarium DNA and DON content, as well as zearalenone, was found, indicating F. graminearum prevalence among the pathogens causing Fusarium head blight in this region. A high occurrence of mycotoxins produced by Alternaria fungi alternariol (82 % of contaminated samples), tentoxin (TEN) (100 %), and tenuazonic acid (79 %) in the grain was revealed. A significant correlation between the content of Alternaria sect. Alternaria DNA and two mycotoxins alternariol monomethyl ether and TEN was found. Significant distinctions were found between different Krasnodarskiy Krai locations in grain contamination levels with Fusarium, Alternaria fungi and mycotoxins.

Identification of stem melanosis of wheat (Pseudomonas cichorii) by real-time PCR

E. V. Voronov — 2024-11-25

The phytopathogenic bacterium, Pseudomonas cichorii, affects a wide range of crops in filed and greenhouse production and causes wheat stem melanosis, which has been regulated by importers of Russian grain products. It is crucial to update the identification method based on real-time polymerase chain reaction (PCR) (PCR-RT). This method helps confirming P. cichorii in wheat samples. A 90 base pair long section of the hrcRST pathogenicity gene cluster was used as the target. Positive results were obtained for reference strains, confirmed by amplicon sequencing. Nucleotide sequences were then compared to the typical strain, DSM 50259. As a result of comparative DNA analysis, the sequences of the direct primer and probe were modified. The possibility of using a modification of 6FAM/BHQ1 dye/quencher available on the territory of the Russian Federation was demonstrated. The specificity of the new PCR-RT primer system PscF/PscHrc751R/PscP1 was assessed using 107 bacterial strains of the genus Pseudomonas, including P. cichorii, P. fuscovaginae, P. syringae, P. trivialis, P. viridiflava, P. chlororaphis, P. lutea and P. orientalis. The DNA of 4 strains (P. poae, P. graminis and 2 strains of P. fluorescens) showed a non-specific reaction at the 35–37 cycle threshold, with an accumulation that did not appear exponential. The analytical sensitivity of the test allows for the detection of P. cichorii at a concentration of 10^1 CFU/mL. The PCR-RV PscF/PscHrc751R/PscP1 test can be used as a screening tool for the detection of P. cichorii in plant products and for the characterization of pure bacterial cultures.

Selection of a δ-latroinsectotoxin fragment from Latrodectus tredecimguttatus venom for efficient bacterial expression

S. A. Timofeev — 2024-11-25

Toxins from the venom of predatory and parasitoid arthropods, such as scorpions, spiders, and parasitoid wasps, are used as promising tools in plant protection against insect pests. In many cases, polyclonal antibodies can be created to study a single molecule in the laboratory, which allows for specific methods of detection and purification. In the present study, heterologous expression of δ-latroinsectotoxin from the venom of the black widow spider Latrodectus tredecimguttatus, as well as its N- and C- terminal fragments, was carried out in Escherichia coli cells at various temperatures and aeration conditions. Regardless of the expression conditions, the accumulation of the recombinant protein in large quantities in the bacterial cells as inclusion bodies was observed only for the C-terminal fragment of the toxin. The high efficiency of expression of this fragment allowed the use of the insoluble protein fraction of the bacterial homogenate for the immunization of mice and the production of antibodies to δ-latroinsectotoxin. The antigen-binding activity of the immunoglobulins was confirmed by immunoblotting of the synthesized toxin fragment in bacteria using a vector with removed leader sequences. The antibodies obtained can be used to detect the black widow spider toxin during its expression in various systems, such as in the creation of genetically modified entomopathogenic fungi or viruses.

Species composition of weeds in soybean Glycine max crops in the Belgorod region

N. N. Luneva — 2024-11-25

The weed species were studied based on monitoring data in soybean crops in the Belgorod region. A total of 37 species of weed plants were found, most of which belong to the families of Compositae, Gramineae, and Cruciferae. The significance of each species in soybean crops was evaluated on its partial activity, which was determined based on both its occurrence and projective cover. Chenopodium album, Echinochloa crusgalli, Amaranthus retroflexus, Fallopia convolvulus and two Setaria species (S. viridis and S. pumila) demonstrated the highest scores of partial activities. Cirsium incanum, Persicaria hydropiper, Convolvulus arvensis, Solanum nigrum, Polygonum aviculare s. str., Xanthium strumarium were shown to have rather high scores of partial activities. About a third of species (13) are low-active: Cyclachaena xanthiifolia, Sonchus arvensis, Euphorbia virgata, Descurainia sophia, Stachys annua, Artemisia vulgaris, Tripleurospermum inodorum, Lactuca serriola, Consolida regalis, Artemisia absinthium, Sonchus asper, Centaurea cyanus, S. italica. Twelve weed species were rated as inactive in soybean crops of the Belgorod region. The results of the study may be used to develop a regional strategy for protecting soybean crops from weeds in the Belgorod region.