The quality of food is one of the emergent points worldwide. Many microorganisms produce toxins that are harmful for human and animal health. In particular, mycotoxins from Fusarium fungi are strictly controlled in cereals. Simple and robust biosensors are necessary for ‘in field’ control of the crops and processed products. Nucleic acid-based sensors (aptasensors) offer a new era of point-of-care devices with excellent stability and limits of detection for a variety of analytes. Here we report the development of a surface-enhanced Raman spectroscopy (SERS)-based aptasensor for the detection of T-2 and deoxynivalenol in wheat grains. The aptasensor was able to detect as low as 0.17% of pathogen fungi in the wheat grains. The portable devices, inexpensive SERS substrate, and short analysis time encourage further implementation of the aptasensors outside of highly equipped laboratories.

Plants, including Triticum aestivum L., are constantly attacked by various pathogens which induce immune responses. Immune processes in plants are tightly regulated by proteases from different families within their degradome. In this study, a wheat degradome was characterized. Using profile hidden Markov model (HMMer) algorithm and Pfam database, comprehensive analysis of the T. aestivum genome revealed a large number of proteases (1544 in total) belonging to the five major protease families: serine, cysteine, threonine, aspartic, and metallo-proteases. Mass-spectrometry analysis revealed a 30% difference between degradomes of distinct wheat cultivars (Khakasskaya and Darya), and infection by biotrophic (Puccinia recondita Rob. ex Desm f. sp. tritici) or necrotrophic (Stagonospora nodorum) pathogens induced drastic changes in the presence of proteolytic enzymes. This study shows that an early immune response to biotic stress is associated with the same core of proteases from the C1, C48, C65, M24, M41, S10, S9, S8, and A1 families. Further liquid chromatography-mass spectrometry (LC-MS) analysis of the detected protease-derived peptides revealed that infection by both pathogens enhances overall proteolytic activity in wheat cells and leads to activation of proteolytic cascades. Moreover, sites of proteolysis were identified within the proteases, which probably represent targets of autocatalytic activation, or hydrolysis by another protease within the proteolytic cascades. Although predicted substrates of metacaspase-like and caspase-like proteases were similar in biotrophic and necrotrophic infections, proteolytic activation of proteases was not found to be associated with metacaspase-like and caspase-like activities. These findings indicate that the response of T. aestivum to biotic stress is regulated by unique mechanisms.

One-hundred-and-fifty strains of streptomycetes have been isolated from gray and dark gray forest soils, as well as from typical chernozem. The isolated st

VIABILITY AND VIRULENCE OF WHEAT LEAF RUST AGENT (Puccinia triticina Eriks.) ISOLATES AFTER LONG TERM PRESERVATION N.S. Zhemchuzhina, M.I. Kiseleva, A.I. Zhemchuzhina, S.A. Elizarova

The antioxidant defense system can be stimulated by growth regulators in plants when they are under stress, such as exposure to pathogens. There are a lot of natural growth regulators on the market, but no research has been carried out yet to determine how effective they are. This field and laboratory study examines the impact of two commonly used Russian growth regulators, Crezacin and Zircon, along with artificial infection with Fusarium culmorum on the antioxidant system of naked oat. The results show that, compared to the control, Crezacin-treated plants had higher contents of low molecular weight fructose and nonenzymatic antioxidants like proline, phenolic compounds, and flavonoids. Zircon-treated plants had a lower content of proline, carbohydrates, and lower total antioxidant activity than the control plants. The obtained data show that Crezacin treatment mainly affected nonenzymatic systems of the antioxidant defense. This treatment was more successful than the Zircon application, which did not show any appreciable effectiveness and was typically associated with an improvement in oat productivity. The treatment with growth regulators and a fungal suspension performed at the flowering phase provided the best effect on the biochemical parameters and productivity of naked oats. Moreover, oat treatment with the pathogen promoted the reproductive capabilities of the plants, while growth regulators helped in avoiding infectious stress.