Wpływ skażenia środowiska siarką, fluorem i metalami ciężkimi na fluorescencji chlorofilu w igłach sosny zwyczajnej (Pinus sylvestris L.)

The photochemical activity of photosystem II (PSII) was measured by chlorophyll a fluorescence intensity of Scots pine needles, from trees growing in various forest experimental areas exposed to air and soil pollution. Fluorescence techniques was used as a no-invasive method of detection injuries of the photosynthetic apparatus. Chlorophyll fluorescence parameters such as PSII photochemical efficiency (Fv/Fm), chlorophyll fluorescence decrease ratio (Rfd) and size of the acceptor pools available to PSII (Sm) indicated seasonal changes in the activity of the photosynthetic apparatus of pine needles. Significant differences in the variable fluorescence parameter rations Fv/Fm and Rfd between the studied sites were found in middle-winter dormancy period in January and also in samples collected in August. Winter inactivation of photosynthesis results in areduction of the photochemical efficiency Fv/Fm and Rfd. Presented results demonstrate that the effect of industrial pollution on Scots pine needles is detectable by of measurements of fluorescence parameters. They showed that Scots pine trees indicated physiological adaptation to environmental pollution and this can be monitored by the fluorescence signals earlier than by other methods.Badano fotochemiczną aktywność fotosystemu II (PS II) igieł sosny zwyczajnej mierząc fluorescencję chlorofilu a igieł trzech populacji rosnących pod wpływem skażenia gleby i powietrza. Analizowano następujące parametry fluorescencji chlorofilu a: Fv/Fm, Rfd i Sm/Fm. Stwierdzono ich sezonowazmie - nność. Istotne różnice statystyczne pomiedzy stanowiskami wzrostu badanych populacji wystąpiły dla parametru Fv/Fm i Rfd w okresie spoczynku zimowego w styczniu. Zaburzenia fotosyntezy zimą prowadzą do redukcji wydajności fotochemicznej wyrażonej stosunkiem Fv/Fm i Rfd. Uzyskane wyniki wskazują iż kondycję drzew iglastych rosnących w skażonym środowisku można ocenić przez pomiar fluorecencji chlorofilu a w igłach. Przedstawione badania wspierają hipotezę zakładającą, że sosna zwyczajna należy do drzew o wyraźnej fizjologicznej zdolności adaptacji do skażonego środowiska

Threats during cryopreservation of seed embryonic axes of woody plants

Cryopreservation in liquid nitrogen (–196℃, LN) is the method of long−term conservation of plant tissues, which has been evolving for many of seed of woody plant species. During cryopreservation protocol to LN in plant cells take place the supercooling tissue water or vitrification, which allows the successful storage. Water content was a significant determining factor with survival of cryostored embryonic axes of woody plants. The protocols of cryopreservation include some steps during preparation of plant material, which could be a source of oxidative stress, phase transition of membranes and destruction in cells

Differential effects of spring reacclimation and deacclimation on cell membranes of Norway spruce seedlings

Two-year-old seedlings of Norway spruce (Picea abies) during spring deacclimation were subjected to controlled reacclimation by exposure to low temperatures of 4/−3°C (day/night) in a cold room. The highest increase in freezing tolerance (by 7°C) was observed after 12 d of low temperature exposure, when shoot water potential (Ψw shoot) decreased to 0.64 MPa. The process of reacclimation was accompanied by an increase in the phospholipid content of needle cell membranes. This increase applied to total (PL) and individual phospholipids: phosphatidylcholine (PC), phosphatidylglycerol (PG), phosphatidylethanolamine (PE) and phosphatidic acid (PA). After being exposed to the low temperature for 18 d, the seedlings were moved into the open air. This caused deacclimation, with an increase in Ψw shoot to −0.36 MPa and a decrease in the total phospholipid content and freezing tolerance of the needles. Significant correlations were observed between freezing tolerance, the membrane permeability (MP) of the needles and the phospholipid content, Ψw shoot and water content of the needles. The results show that during spring deacclimation, Norway spruce seedlings can be subjected to reacclimation, which is reflected in the phospholipid content, the biophysical changes of the membranes, and the freezing tolerance of the seedlings. During both spring deacclimation and reacclimation, water content in the needles plays a critical role in the cold tolerance of spruce seedlings

Effect of freezing desiccation on cold hardiness, ROS, membrane lipid levels and antioxidant status in spruce seedlings

The symptoms of oxidative stress and antioxidative response were investigated on Norway spruce seedlings subjected to freezing desiccation conditions. Three-year-old seedlings were exposed to freezing desiccation at -3oC and -10oC for 45 days in two acclimation stages: autumn (October) and winter (January). The stress enhanced the production of reactive oxygen species (ROS): superoxide radical anion (O2.-), and hydrogen peroxide (H2O2). Concentrations of low molecular antioxidants: glutathione (GSH), ascorbic acid (AsA) and a-tocopherol declined at both low temperatures and acclimation stages. The activity of superoxide dismutase (SOD) increased with ROS production, while guaiacol peroxidase (POX) activity decreased. The freeze-induced desiccation of needles was significantly correlated with the cold hardiness (LT50), the level of low-molecular antioxidants, and POX activity, but not with SOD activity. Under extreme freezing desiccation conditions, these reactions continued, leading to the degradation of membrane phospholipids and a strong decrease in cold hardiness. The results show that membranes are the primary site of injury induced by ROS, produced under the influence of low temperature combined with dehydration. The acclimation response of Norway spruce needles to the oxidative stress generated by long-term cold and/or freezing desiccation is discussed