F690-F740 is more suitable than F690/F740 for mapping the regeneration of Cd-induced chlorosis in poplar leaves by fluorescence imaging

The effect of cold treatment on concentration of biogenic amines was compared in the moderately frost-sensitive Triticum aestivum cv. Chinese Spring wheat genotype and in the frost-tolerant Chinese Spring (Cheyenne 5A) and the frost-sensitive Chinese Spring (T. spelta 5A) chromosome 5A substitution lines. To see the dynamics of changes, the plant material was collected after 0d, 1d, 3d, 7d and 21d of treatment at 2°C. Quantitative determination of biogenic amines was accomplished by chromatographic method. The cold treatment caused especially great increase in putrescine and spermidine levels. Chromosome 5A affected the cold induced increase in putrescine content, being larger after 21d of cold treatment in the frost-tolerant Chinese Spring (Cheyenne 5A) compared to the sensitive genotypes, which may indicate the role of putrescine accumulation in frost tolerance

Significance of antioxidative defence under long-term Cd stress

Cadmium is a highly toxic heavy metal which causes strong oxidative stress thereby inactivating PSII and the photosynthetic electron transport. However, plants acclimate to moderate Cd stress under longer treatment. Here, the role of antioxidative defence was studied during this acclimation. Micropropagated poplar plants were treated with 10 μM Cd(NO3)2 from their four-leaf-stage for four weeks. Increase in the malondialdehyde content and in the ratio of inactive, quenching PSII reaction centres (ΦNF) was observed in the first two weeks of the treatment. Starting from the third week both parameters decreased in parallel to the rise in the ascorbate peroxidase activity and B-carotene content, both are important in the antioxidative defence in chloroplasts. Therefore, an acute and an acclimation phase were identified as a consequence of the delay in activation of antioxidative defence mechanisms, the protective role of which is important in the acclimation to moderate Cd stress

Detection of the vitalization effect of Tuber mycorrhiza on sessile oak by the recently-innovated FMM chlorophyll fluorometer

Mycorrhizae enhance the viability of forest trees by the protection against drought and nutrient deficiencies. Here a FluoroMeter Modul (FMM) Chl a fluorometer developed on the Department of Atomic Physics of the Budapest University of Technology and Economics, was used to typify symbiotic relationship between Quercus and Tuber which has economic impact due to its fruiting body. The actual quantum efficiency photosystem II showed strong correlation with low mycorrhizations up to the level of average mycorrhiztion in sessile oak seedling population, which refers to strict host control on mycorrhization. F690/F735 ratio of peak fluorescence, which is known to correlate negatively to leaf chlorophyll content, implicated that the higher mycorrhization caused probably stronger leaf area expansion. Therefore, the presence of Tuber mycorrhiza on Quercus roots enhanced the vitality of oak trees. The portable and relatively low-price FMM fluorometer proved to be an adequate tool for serial in situ vitality measurements

Mycorrhizal colonization by Tuber aestivum has a negative effect on the vitality of oak and hazel seedlings

Ectomycorrhizal fungi have a great impact on the ecosystem in boreal and temperate regions, and it has commercial, silvicultural and crop importance as well. The summer truffle (Tuber aestivum), a common mycorrhizal partner of several trees, is a valuable ectomycorrhizal fungus since its fruit bodies (ascomata) are a popular and expensive product on the global markets. To understand the physiology and ecology of a natural forest or a plantation, the participants and relationships between them should be examined. Hence, the maximal quantum efficiency of photosystem II centers, that is vitality of half a year old oak (Quercus robur) and hazel (Corylus avellana) seedlings inoculated with summer truffle was measured. The relation between the vitality of the plants and the rate of colonization of the fungus was examined applying single and multiple linear regressions. In the case of the oak seedlings contamination of Scleroderma spp. morphotype colonization was observed. Negative relationship between rate of colonization and the vitality was detected in the case of hazel seedling and non-contaminated oak seedlings. Multiple linear regression analysis revealed that there is no effect of truffle and contaminant fungi together, but alone the truffle has a negative impact. Consequently, the Scleroderma ectomycorrhiza seemed to have a balancing effect on the negative impact of summer truffle

Antioxidative defence mechanism contributes to desiccation tolerance in Haberlea rhodopensis population naturally exposed to high irradiation

Drought induced stress is one of the most important among the environmental challenges. Haberlea rhodopensis, a chlorophyll-retaining resurrection plant, can survive desiccation to air-dry stage in its usual low irradiance habitat (“shade” plants). Nevertheless, in the past years, some populations living under high irradiance (“sun” plants) have been also discovered with the same ability to survive dehydration. In order to clarify the adaptation mechanisms to a high irradiation habitat, superoxide dismutase (SOD) activity determined by activity staining on polyacrylamide gels and malondialdehyde (MDA) content of sun and shade plants collected from high and low irradiance environment, respectively, were studied. Desiccation induced a significantly higher induction in SOD activity and thus a smaller increase in the MDA content in sun compared to shade plants. The MDA content and SOD activity was restored in both sun and shade plants after six-day rehydration. Nevertheless, the SOD activity remained higher in rehydrated sun leaves compared to the well-hydrated initial stage. The early enhancement of SOD activity in dehydrating sun plants contributes to the higher stress tolerance of these populations

Responses of Szarvasi-1 energy grass to sewage sludge treatments in hydroponics

Sewage sludge (SS) originating from communal wastewater is a hazardous material but have a potentially great nutritive value. Its disposal after treatment in agricultural lands can be a very economical and safe way of utilization once fast growing, high biomass, perennial plants of renewable energy production are cultivated. Szarvasi-1 energy grass (Elymus elongatus subsp. ponticus cv. Szarvasi-1), a good candidate for this application, was grown in hydroponics in order to assess its metal accumulation and tolerance under increasing SS amendments. The applied SS had a composition characteristic to SS from communal wastes and did not contain any toxic heavy metal contamination from industrial sludge in high concentration. Toxic effects was assessed in quarter strength Hoagland nutrient solution and only the two highest doses (12.5-18.75 g dm-3) caused decreases in root growth, shoot water content and length and stomatal conductance whereas shoot growth, root water content, chlorophyll concentration and the maximal quantum efficiency of photosystem II was unaffected. Shoot K, Ca, Mg, Mn, Zn and Cu content decreased but Na and Ni increased in the shoot compared to the unamended control. The nutritive effect was tested in 1/40 strength Hoagland solution and only the highest dose (12.5 g dm-3) decreased root growth and stomatal conductance significantly while lower doses (1.25-6.25 g dm-3) had a stimulative effect. Shoot K, Na, Fe and Ni increased and Ca, Mg, Mn, Zn and Cu decreased in this treatment. It was concluded that SS with low heavy metal content can be a potentially good fertilizer for high biomass non-food crops such as Szarvasi-1 energy grass