This study showed that several mechanisms of the basal resistance of winter triticale to Microdochium nivale are cultivar-dependent and can be induced specifically during plant hardening. Experiments and microscopic observations were conducted on triticale cvs Hewo (able to develop resistance after cold treatment) and Magnat (susceptible to infection despite hardening). In cv. Hewo, cold hardening altered the physical and chemical properties of the leaf surface and prevented both adhesion of M. nivale hyphae to the leaves and direct penetration of the epidermis. Cold-induced submicron-and micron-scale roughness on the leaf epidermis resulted in superhydrophobicity, restricting fungal adhesion and growth, while the lower permeability and altered chemical composition of the host cell wall protected against tissue digestion by the fungus. The fungal strategy to access the nutrient resources of resistant hosts is the penetration of leaf tissues through stomata, followed by biotrophic intercellular growth of individual hyphae and the formation of haustoria-like structures within mesophyll cells. In contrast, a destructive necrotrophic fungal lifestyle occurs in susceptible seedlings, despite cold hardening of the plants, with the host epidermis, mesophyll and vascular tissues being digested and becoming disorganized as a result of the low chemical and mechanical stability of the cell wall matrix. This work indicates that specific genetically encoded physical and mechanical properties of the cell wall and leaf tissues that depend on cold hardening are factors that can determine plant resistance against fungal diseases.

This paper presents a study of the metabolic response (dark respiration intensity, photosystem II efficiency, metabolic activity) and the yield of barley treated with 24-epibrassinolide and subjected to high-temperature stress. Transport of exogenously applied 24-epibrassinolide in barley and changes in the profile of brassinosteroids that may occur in tissues after 24-epibrassinolide application were also studied. The water solution of 24-epibrassinolide (0.005 and 0.25 mg dm -3 ) was applied via infiltration of the first and second leaves of 12-day-old seedlings. Control plants were treated with water solution of hormone solvent (ethanol). Fifteen-day-old plants were subjected to hightemperature stress (42°C for 3 h). The influence of hormone treatment and stress conditions was investigated in the first and second leaves based on measurements of PSII efficiency. The aftereffect of plant treatment was investigated in the seventh leaf (measurements of PS II efficiency, dark respiration intensity, metabolic activity). The transport efficiency of 24-epibrassinolide exogenously applied to the first and second leaves, as well as the profile of other brassinosteroids, was also measured on the seventh leaf. Finally, yield formation was estimated. 24-epibrassinolide showed protective action, which manifested itself in the improved functioning of PSII, but this was observed in case of higher hormone concentration and only for the first, older leaf. The PSII efficiency of the seventh leaf was similar in plants treated with brassinosteroid and in the control plants, whereas the respiration intensity and metabolic activity decreased in plants previously treated with higher concentration of 24-epibrassinolide. The use of a higher hormone concentration at the seedling phase ultimately resulted also in lower crop yield. Brassinosteroids-brassinolide and castasterone-were detected in barley leaves. 24-epibrassinolide was found only in trace amounts in control plants. Its exogenous application directly to the apoplast of the first and second leaves resulted in an increase in the 24-epibrassinolide content in the seventh leaf, but did not depend on whether a high or low concentration had been applied to the plants.

The exposure of winter triticale to cold promotes genotype-dependent resistance to fungal pathogen. We present the evidence that structural and chemical modifications of the cell wall components induced by cold can be correlated with the resistance against fungal infection. Our results showed that cellulose of hardened triticale cv. Hewo (able to develop resistance after cold treatment) has more compact and integrated structure, thicker and longer fibres when compared to cv. Magnat (susceptible to fungal infection despite plant hardening). Such structure of cellulose limits water sorption, favours stronger bonding the water of crystallisation to macromolecules, impedes depolymerisation process during decomposition, and finally results in higher thermal stability of cell wall. Furthermore, the lignin composition is drastically modified in resistant plants. Pattern of the thermal decomposition indicates higher molecular mass and more complex structure of lignin, followed by the higher thermal stability. We conclude that specific structure of lignocellulosic cell wall of the resistant plants forms a barrier for fungal enzymes digesting host tissue as well as can resist better the mechanical pressure of hyphae.

Abstract:The effect of soil drought (10 days) on the growth of plants, the accumulation of water and leakage of electrolytes, gas exchange, the contents of chl a + b and carotenoids in leaves and photochemical activity of photosystem II was studied at the seedling stage by transient fluorescent analysis in 20 of the popular varieties of polish spring wheat. Drought caused a particularly strong reduction in vigor of growth of seedlings, net photosynthesis rate and triggered an increase in electrolyte leakage from the leaves. Certain varieties during the drought demonstrated relatively intense CO 2 assimilation at low water loss through transpiration. The varieties tested were significantly different in terms of tolerance to drought of the processes of gas exchange and seedlings development. Photochemical processes in PSII showed high tolerance to drought and at the same time low differentiation among varieties. The results obtained suggested that tolerance of growth parameters to drought and CO 2 assimilation at the seedling stage may alleviate consequent depression of final yield of the grain.

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Chemical micro-traces belong to the group of forensic traces. In the case of this type of traces, we are dealing with group identification. Nonetheless, they are a very valuable and often the only procedural source of information about a crime that has taken place, and their evidential significance increases, in particular, in situations where it has not been possible to secure forensic traces in the course of the conducted activities, which would allow for individual identification of a perpetrator. The purpose of this article is to show the importance of chemical micro-traces in clarifying the circumstances of an incident and identifying a perpetrator on the basis of an opinion made in 2020 at Forensic Laboratory of the Voivodeship Police Headquarters in Kraków concerning a road accident which resulted in the death of a young woman.

Redox activity was measured in vegetative and generative apical parts (5 mm of the stem) and youngest leaves of winter (cv. "Gó rczań ski") and spring (cv. "Młochowski") rape. Both genotypes were cultured under the same growth conditions (17/15 ∞C day/night, 16 h photoperiod), but winter rape was additionally vernalized (5/2 ∞C day/night, 56 days) in order to induce the generative development. The cyclic voltammetric method was used to measure the redox potential of samples in the presence of Fe 3+ ions. Changes in the redox activity were compared with changes in riboflavin content and activities of antioxidative enzymes: superoxide dismutase (SOD) and catalase (CAT). The higher level of Fe 3+ ions and riboflavin detected in generative apices and leaves of winter and spring varieties indicated that electrons (and their donors) were present at a lower level in these organs in comparison with the vegetative ones. On the contrary, SOD and CAT activity were lower in generative than in vegetative organs. This confirms changes in the redox balance and involvement of oxygen radicals in the generative development of rape plants. The similarity of the measured parameters between winter and spring varieties indicates that the observed changes are independent of the way of generative induction (vernalization). Riboflavin can serve as one of the electron carriers between other oxidation-reduction substances.