Diversity of Fusarium Species and Their Mycotoxins in Cereal Crops from the Asian Territory of Russia

Up-to-date information on the occurrence of Fusarium fungi and their mycotoxins in the grain of wheat, barley and oats grown in the Urals and West Siberia in 2018‒2019 is presented. Mycological analysis of grain revealed at least 16 species of Fusarium fungi. The F. sporotrichioides, F. avenaceum, F. poae, and F. anguioides were predominant, and the proportions of these species among all Fusarium fungi found in the grain were 31, 20, 19, and 13%, respectively. Fusarium graminearum and its mycotoxin deoxynivalenol (DON) are often occurred in grain mycobiota of cereal crops on the territory of both the Urals and West Siberia. New records of fungal species that are rare in the Asian territory of Russia were detected: F. langsethiae and F. sibiricum, which are mainly producers of type A trichothecene mycotoxins, were found in the Kurgan and Kemerovo regions, respectively. In addition, F. globosum that is able to produce fumonisins was detected in Altai Krai and Omsk region. The diversity of Fusarium species was higher in wheat and barley grain samples than in oats. The HPLC-MS/MS method was used to analyse the content of 19 mycotoxins produced by Fusarium fungi. The highest diversity of mycotoxins was found in wheat grain (maximum 12), compared with oats (9) and barley (8). The T-2 and HT-2 toxins, DON, nivalenol, moniliformin (MON) and beauvericin (BEA) occurred more often in the grain samples, compared with other mycotoxins, but their amounts varied significantly, depending on the weather conditions in sampling year and the plant species. The average content of DON (maximum amount was 375 µg/kg) in wheat grain was 5 times higher than its average content in barley grain, and this mycotoxin was not detected in oat grain. The contamination with T-2 and HT-toxins (maximum amounts were 2652 μg/kg and 481 μg/kg, respectively), as well as with BEA (maximum amount was 49 μg/kg) was typical for barley and oat grain samples. The content of MON (maximum amount was 50 μg/kg) in the grain of three different small grain cereals was similar.

Resistance of oat breeding lines to grain contamination with Fusarium langsethiae and T-2/HT-2 toxins

Fusarium disease of oats reduces yield quality due to decreasing germination that is caused by the contamination of grain with mycotoxins produced by Fusarium fungi. The aim of this study was to characterize the resistance of naked breeding lines of oats to fungal grain infection and to contamination with T-2 and HT-2 toxins. Thirteen naked oat breeding lines and two naked varieties, Nemchinovsky 61 and Vyatskiy, as well as a husked variety Yakov, were grown under natural conditions in the Nemchinovka Federal Research Center in 2019-2020. The contamination of grain with fungi was determined by the mycological method and real-time PCR. The analysis of mycotoxins was carried out by ELISA. In oats, Alternaria (the grain infection was 15-90 %), Cochliobolus (1-33 %), Cladosporium (1-19 %), Epicoccum (0-11 %), and Fusarium (3-17 %) fungi prevailed in the grain mycobiota. The predominant Fusarium species were F. poae (its proportion among Fusarium fungi was 49-68 %) and F. langsethiae (29-28 %). The highest amounts of F. langsethiae DNA ((27.9-71.9) × 10-4 pg/ng) and T-2/HT-2 toxins (790-1230 μg/kg) were found in the grain of husked oat Yakov. Among the analysed naked oat lines, the amount of F. langsethiae DNA varied in the range of (1.2-42.7) × 10-4 pg/ng,and the content of T-2/HT-2 toxins was in the range of 5-229 μg/kg. Two oat breeding lines, 54h2476 and 66h2618, as well as a new variety, Azil (57h2396), can be characterized as highly resistant to infection with Fusarium fungi and contamination with mycotoxins compared to the control variety Vyatskiy.

Characterization of resistance of winter wheat varieties to Fusarium head blight

In this study, naturally and artificially inoculated winter wheat varieties were studied with respect to their productivity and resistance to Fusarium head blight (FHB). We used the following set of disease assessment parameters: the percentage of visually and latent Fusarium-damaged grains (FDG); the DNA content of Fusarium fungi; the productivity of inoculated plants compared with non-inoculated plants; and the amount of mycotoxins in the grain. In case of naturally infected grains, the average FDG was found to be about 6.1 % (range of 0–15 %). The amount of DNA of Fusarium graminearum was found to be in the range of (1.1–42.7) × 10–5 ng/ng wheat DNA. The mycotoxin deoxynivalenol (DON) was detected in 15 samples of grain from plants that were grown under natural infection. The maximum DON amount was found to be 420 μg/kg. Fumonisin B1 (FB1) was not be detected in naturally infected grain. In case of artificially inoculated plants, the average FDG was found to be 25.8 % (2–54 %). The amount of F. graminearum DNA was found to be significantly higher (4.24– 49.8) × 10–3 ng/ng than it was detected in grain of non-inoculated plants. The wheat varieties inoculated with F. graminearum contained DON in high amounts from 20255 to 79245 μg/kg. Furthermore, a significant amount of FB1 was detected in all wheat varieties in the range of 980–20326 μg/kg. Among the analysed wheat varieties, Adel was characterized to be the most resistant to fungal infection as well as to the contamination by mycotoxins. Antonina, Lebed and Pamyat varieties were classified more relatively resistant than that of other varieties, and Utrish variety was found to be the most susceptible to FHB. The similar resistance of wheat varieties against F. graminearum and F. verticillioides infection was recorded, and the interactions between the fungi during the colonization of grain were shown.