Acquired stress resistance is the result of mild stress causing the acquisition of resistance to severe stress of the same or a different type. The mechanism of “same-stress” resistance (resistance to a second, strong stress after mild primary stress of the same type) probably depends on the activation of defense and repair mechanisms specific for a particular type of stress, while cross-stress resistance (i.e., resistance to a second, strong stress after a different type of mild primary stress) is the effect of activation of both a specific and general stress response program, which in Saccharomyces cerevisiae yeast is known as the environmental stress response (ESR). Advancements in research techniques have made it possible to study the mechanism of cross-stress resistance at various levels of cellular organization: stress signal transduction pathways, regulation of gene expression, and transcription or translation processes. As a result of this type of research, views on the cross-stress protection mechanism have been reconsidered. It was originally thought that cross-stress resistance, irrespective of the nature of the two stresses, was determined by universal mechanisms, i.e., the same mechanisms within the general stress response. They are now believed to be more specific and strictly dependent on the features of the first stress.

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The study analysed the effect of silver nanoparticles (AgNPs) on seed germination, field emergence and the physiological parameters of seedlings of two bean cultivars, ‘Bali’ and ‘Delfina’, under normal and chill temperatures. AgNPs solutions (0.25, 1.25 and 2.5 mg dm−3) were applied together with the microbial preparation Nitragina (containing Rhizobium leguminosarum bv. phaseoli) on seeds as a short-term pre-sowing treatment. Low concentrations of AgNPs (0.25, 1.25 mg dm−3) had an immediate beneficial effect, resulting in fast and uniform germination in laboratory and field conditions, as well as a positive effect in the later stages of seedling development, manifested as an increase in the average seedling height, fresh and dry weight and net photosynthesis. Particularly, favourable effects were noted in suboptimal temperature conditions, suggesting that AgNPs activate plant mechanisms of tolerance to environmental stress. The highest concentration tested of AgNPs was not particularly effective for the plants but had a strong antimicrobial effect, which was beneficial in period of seed germination, but at the later stage of plant development was unfavourable probably due to disruption of symbiosis between the bean seedlings and rhizobia.

In our investigation, the chemical composition and bioactive potential of leaf buds of raspberry, blackberry, and a raspberry-blackberry hybrid were determined. Antioxidant and antimicrobial properties were tested in water (W), ethanol-water (EW), and glycerol-water (GW) extracts from the buds. These plant organs contain relatively large amounts of minerals, especially Fe. The total antioxidant capacity (TAC) measured by the ABTS and DPPH methods ranged from 2.86 to 12.19 and 6.75 to 24.26 mmol per 100 g fresh weight (FW) of buds, respectively. TAC values were generally higher in the raspberry than in the case of blackberry and raspberry-blackberry hybrid extracts. The antioxidant properties of the extracts were strongly positively correlated with their content of total phenolic (TP). No such relationship was noted for ascorbic acid (AA), whose concentration in all extracts was at a similarly low level. Antioxidant properties determined in vitro were confirmed for the GW extract from raspberry leaf buds in biological test based on the growth parameters of Δsod1 Saccharomyces cerevisiae mutant cells in hypertonic medium. The extracts also exhibited strong antibacterial properties against Staphylococcus aureus and Enterococcus faecalis and weaker against Enterobacter aerogenes. The studied leaf buds could be therefore an unconventional source of minerals, natural antioxidants and antibacterial compounds with potential applications in the food, pharmaceutical, and cosmetics industries.

A correlation is known to exist in yeast and other organisms between the cellular resistance to stress and the life span. The aim of this study was to examine whether stress treatment does affect the generative life span of yeast cells. Both heat shock (38 degrees C, 30 min) and osmotic stress (0.3 M NaCl, 1 h) applied cyclically were found to increase the mean and maximum life span of Saccharomyces cerevisiae. Both effects were more pronounced in superoxide dismutase-deficient yeast strains (up to 50% prolongation of mean life span and up to 30% prolongation of maximum life span) than in their wild-type counterparts. These data point to the importance of the antioxidant barrier in the stress-induced prolongation of yeast life span.