Air pollution in the places of Betula pendula growth and development changes the physicochemical properties and the main allergen content of its pollen
Pollen allergy becomes an increasing problem for humans, especially in the regions, where the air pollution level increases due to the traffic and urbanization. These factors may also affect the physiological activity of plants, causing changes in pollen allergenicity. The aim of the study was to estimate the influence of air pollutants on the chemical composition of birch pollen and the secondary structures of the Bet v1 protein. The research was conducted in seven locations in Malopolska region, South of Poland of a different pollution level. We have found slight fluctuations in the values of parameters describing the photosynthetic light reactions, similar spectra of leaf reflectance and the negligible differences in the discrimination values of the δ13C carbon isotope were found. The obtained results show a minor effect of a degree of pollution on the physiological condition B. pendula specimen. On the other hand, mean Bet v1 concentration measured in pollen samples collected in Kraków was significantly higher than in less polluted places (p = .03886), while FT-Raman spectra showed the most distinct variations in the wavenumbers characteristic of proteins. Pollen collected at sites of the increased NOx and PM concentration, show the highest percentage values of potential aggregated forms and antiparallel β-sheets in the expense of α-helix, presenting a substantial impact on chemical compounds of pollen, Bet v1 concentration and on formation of the secondary structure of proteins, what can influence their functions.
Comparison of the maximum photochemical efficiency of PSII of B. pendula, Fv/Fm ( Fig 1A ) XA, shows a similar efficiency of the light-dependent processes of photosynthesis in plants growing on all sites. In all analyzed trees, the Fv/Fm parameter takes the values of 0.78–0.82, while the optimal value for plants in the vegetative state is above 0.83 [ 50 ]. Therefore, the Fv/Fm values do not indicate disturbances during light reactions in photosynthesis, caused by exposure to the negative effects of weather conditions. Greater variation between subjects was observed in the Fv/F 0 values ( Fig 1B ) . A significant decrease of Fv/F 0 took place in the birch growing in Brunary (BR), which reveals some structural damage to the thylakoids, which, however, had little effect on photosynthetic electron transport within PSII [ 51 ]. The Chla fluorescence parameters are considered very informative and effective in assessing the physiological condition of plants. The maximum quantum efficiency of PSII (Fv/Fm) is very often used as a reliable indicator of photosynthetic apparatus activity [ 48 ]. It has been proven that the value of Fv/F 0 is a more sensitive indicator of environmental stress than Fv/Fm [ 49 ]. The greatest differences in the infrared part of the spectrum (700–1000 nm) were also observed between trees from BA (highest values) and GO (lowest values), Fig 2 . The reflectance intensity in this range is mainly determined by the spatial structure of the tissues in the leaf and the ultrastructure of the parenchyma cells. The mutual position of the cell wall and protoplasm as well as the spaces between chloroplasts and the cell wall and protoplasm play an important role [ 56 ]. The highest percentage values of the reflectance coefficient in the green spectrum were observed in the plant growing in BA, Fig 2 , insert . It is associated with a reduction in the chlorophyll content, which is often observed in plants growing under abiotic stress conditions, including…
Iwona Stawoska, Institute Of Biology, Pedagogical University Of Krakow, Kraków, Dorota Myszkowska, Department Of Clinical, Environmental Allergology, Jagiellonian University Medical College, Jakub Oliwa, Andrzej Skoczowski