Adaptive responses to high salinity of two subspecies of Aster tripolium on different nitrogen sources

ABSTRACT The effects of NaCl salinity, different N-sources (nitrate or ammonium), as well as pH on the major enzymes of N-metabolism and total antioxidant capacity were investigated in two subspecies of Aster tripolium L., A. tripolium ssp. tripolium, a maritime halophyte, and A. tripolium ssp. pannonicus, endemic on the continental alkaline salty meadows. Differences in their biochemical and physiological responses to the experimental conditions are in agreement with their evolutional adaptation either to the fluctuating coastal circumstances or to the more constant salinity level on the alkaline salty meadows. Accordingly, A. tripolium ssp. tripolium reacted more sensitively to salinity while A. tripolium ssp. pannonicus showed less physiological flexibility and more stable performance. Soil salinity is an important agricultural problem. One possible way to use affected fields is planting salt tolerant crops such as Aster tripolium L.. Aster tripolium (Asteraceae/Compositae) is a typical halophyte species with two horizontally isolated subspecies (Borhidi 1995). The two subspecies are very different concerning their habitats, morphology and physiology. The ssp. tripolium is a maritime halophyte, while ssp. pannonicus is common on the continental alkaline salty meadows. Morphological differences are obvious in leaf size and shape, leaf colour, leaf number and growth habitus. Both ssp. accumulate inorganic ions even at low external concentrations. Physiologically sea aster was more intensively studied (Shennan et al. 1987ab) because of its recently increasing commercial importance as halophyte crop. Its value is the mild salty taste and high protein content of the succulent leaves. The ssp. pannonicus inhabits salty meadows rich in NaHCO 3 thus having high pH. Materials and Methods Two subspecies of Aster tripolium were examined in our experiments: ssp. tripolium and ssp. pannonicus. Plants were grown hydroponically in complete modified Hoagland nutrient solution of different pH values (from 4 to 10). In one container, 7 plants of each of the subspecies were placed and were grown for 6 weeks under controlled conditions in greenhouse at an additional light intensity of 100 µmol m -2 s -1 for 12 hours. Day/night temperature was 24/18ºC. The pH values were controlled and adjusted daily by addition of HCl or NaOH. On the basis of protein content data (Bradford 1976), pH 5 and 8 were selected for further experiments when plants were grown at 0, 50, 100, 200 and 300 mM NaCl concentrations added to the complete nutrient solution. The nutrient solutions also altered in there nitrogen source which was nitrate or ammonium, respectively. Chlorophyll Results and Discussion Aster tripolium ssp. tripolium obviously suffered under low salt conditions combined with high pH values as shown by the low pigment concentrations. In both subspecies, qualitative and quantitative alterations were observed in protein concentrations with increasing salinity and pH values. At low pH and medium salt concentrations, ssp. tripolium had higher protein levels than ssp. pannonicus, while at high pH values ssp. pannonicus had higher performance. Very high Na + concentrations were accumulated in the leaves in both pH regions. Calcium is known to play a special role in tolerance under salinity. Surprisingly, in ssp. pannonicus Ca 2+ accumulation increased under the highest NaCl concentrations (300 mM) while in contrast, ssp. tripolium showed a decreasing tendency in calcium accumulation under increasing external salinity. In the following pH 5 was selected and the nitrogen source was nitrate or ammonium, respectively. Our intention was to investigate enzymes involved in nitrogen metabolism as a function of sodium concentration. Nitrate reductase (NR), glutamine synthetase (GS) activity and total antioxidant capacity were measured in both leaves and roots. Control (0), 10, 50, 100 and 200 mM NaCl was added to the nutrient solutions with both nitrogen sources. One of our interesting results was that young leaves of Aster tripolium ssp. tripoliu

Changes in cyclic hydroxamic acid content of various rye varieties for the effect of abiotic stress

ABSTRACT According to our opinion cyclic hydroxamic acids (cHx-s) are stress metabolites. For the effect of stress the level of cHx rises and through their various biological effects the cHx-s prevent the plants from the harmful influences of stress. In these experiments I examined the changes in cHx-content of rye plants (Secale cereale and S. cereanum varieties). The plants were grown in nutrient solution and were treated with 100mM NaCl. My hypothesis in the case of shoots was proved: the cHx-content of shoots of all varieties changed according to stress syndrome. I could not demonstrate early decrease in cHx-content of roots, but I suppose that it had occurred before my first observation

szalai.indd

ABSTRACT Two-week-old maize plants were treated with 50 or 100 mM NaCl for seven days. Leaves and roots were collected for measurements on salicylic acid and antioxidant enzyme activity on the 1 st , 3 rd and 7 th days of treatment and after four days of recovery. The quantum yield of photosystem II decreased after 7 days in maize plants treated with 100 mM NaCl. There were no changes in the catalase and ascorbate peroxidase activity. The glutathione-S-transferase, glutathione reductase and guaiacol peroxidase activities increased. There were no changes in the level of endogenous free and bound salicylic acid. The free o-hydroxy-cinnamic acid (oHCA) content increased after 7 days in the leaves, while the bound oHCA level increased after 4 days of recovery. It has been concluded that oHCA may play an important role in stress processes

Effects of supplemental UV-B radiation on the photosynthesis -physiological properties and flavonoid content of beech seedlings (Fagus sylvatica L.) in outdoor conditions

ABSTRACT Responses of beech seedlings to supplemental UV-B radiation were investigated during three consecutive seasons, in three repeated experiments. Our attention was paid on the alteration of the photosynthetic pigment composition -especially on the xanthophyll cycle pigments -chlorophyll fluorescence parameters, furthermore the accumulation of UV-B absorbing compounds in leaves, the specific leaf mass and leaf water content. The enhanced UV-B radiation generally affected significantly neither photochemical efficiency of PSII, nor photosynthetic pigment composition. UV-B radiation induced some protective mechanisms, thus VAZ-pool increased in beech leaves in every experiment, parallel with the enhancement of non-photochemical quenching. Amount of UV-B absorbing compounds in leaves increased under enhanced UV-B, but no significant changes were observed in the specific leaf mass. Sensitivity of plants to UV-B is largely influenced by other environmental factors and experimental conditions

Root development and drought tolerance of wheat-barley introgression lines

ABSTRACT nterspecific hybridization makes it possible to transfer useful traits, such as stress tolerance, earliness and various desirable traits from one species into another. Addition, substitution and translocation lines developed from wheat-barley (Triticum aestivum L. x Hordeum vulgare L.) hybrids were analyzed to determine how the added barley chromosomes (or segments) influence agronomy traits in wheat. Experiments were carried out at Georgikon Faculty, Keszthely. First we checked the seeds germinating power and the early development of shoots and roots. The drought-tolerance was tested under rain shelter in the field. The morphological and agronomic traits of the introgression lines were studied. Data were obtained for root-shoot ratio (EC: 30-31), heading time (earliness), plant height, morphology and length of ear, components of grain yield. The use of this genetic material in wheat breeding programs can result in new varieties with better adaptation

Body mass index percentiles for rural Bengalee pre-school children aged 2-6 years, in comparison with the WHO reference and other studies

ABSTRACT Objective: Compare the body mass index (BMI) percentiles of the rural Bengalee children with those in two recently developed international references: the WHO and the US Centers for Disease Control and Prevention (US CDC) growth references and two other studies. Design: A cross-sectional ethnic based survey. Setting: Thirty randomly selected villages, from rural areas of Purulia, Paschim Medinipur and Darjeeling. Subjects: 1,872 preschool children aged 2-6 years. Results: BMI percentiles were established using the LMS method, and were compared with the percentiles of the WHO reference, the US CDC reference and two other studies. BMI distributions and growth patterns in Bengalee preschool children were dramatically different from those in the two international reference populations. Compared with the international reference populations, rural Bengalee boys and girls (2-6 years) had substantially lower BMI percentiles than their counterparts in the reference populations. Conclusions: The present study described the different patterns of BMI values at the regional/ethnic level, and these values are useful as a reference for comparing different regions and for monitoring changes over time in Bengalee and children of Indian subcontinent. Higher proportions of children with extreme values in uni-directions indicate that Bengalee children currently facing an increasing level of undernutrition. Materials and Method

Variation in ecophysiological traits of dominant species in open and closed stands of a semiarid sandy grassland

ABSTRACT Under the continental climate of the Carpathian Basin, semiarid grasslands represent one of the widespread vegetation types. Due to overgrazing and other disturbances, most of the semiarid grasslands in Hungary are the mosaics of more or less degraded patches. Our work has focused on the variations in the ecophysiological traits of the common dominant species in a moderately degraded (vegetation cover 70%) and a strongly degraded stand (vegetation cover 27%) of Potentillo-Festucetum pseudovinae community. As a result of low soil moisture content, species experienced significantly higher leaf water saturation deficit in the open stand. Carotenoid pool was larger for all the species in the strongly degraded stand. The protective xanthophyll cycle pool was also higher in the strongly degraded stand, and reached 30-33% of the total carotenoid content. The potential photochemical efficiency (F v /F m ) was lower for monocot species. There was a decrease in the F v /F m values at noon, which was larger in the strongly degraded stand

Effects of cellulase-containing enzymes on auxin heterotrophic and autotrophic tobbaco tissue cultures

ABSTRACT During the digestion of cell wall by cellulases, rapid cell death of auxin heterotrophic and autotrophic tobacco tissue cells has been observed. Under these conditions a considerable amount of H 2 O 2 is secreted into the medium. It is suggested that the rapid cell death induced by cellullysin is partly a result of the hypersensitive defense reaction against cellulysin from the parasitic fungus Trichoderma viride. The absolute amount of secreted H 2 O 2 is higher in the case of heterotrophic cells, but the quantity of H 2 O 2 is greater in the medium of auxin autotrophic cultures as compared with control cells without cellulysin. These cells emit more cellulase-dependent ethylene than the auxin heterotrophic line. Cellulysin induces an increasing intracellular H 2 O 2 level only in the cells of auxin heterotrophic tissues. There are differences between the two cell lines in the change in cytosolic Ca 2+ concentration in response to exogenous H 2 O 2

and the 6 th Hungarian Conference on Photosynthesis, 2005

Changes of glutathione S-transferase activities and gene expression in Triticum aestivum during polyethylene-glycol induced osmotic stres