The Physiology and Biochemical Tolerance of Cabbage to Se (VI) Addition to the Soil and by Foliar Spraying

The effects of selenium (Se) (VI) soil fertilization with 2 μg Se L^?1 or foliar spraying twice with 20 mg Se L^?1 in the form of sodium (Na) selenate on the physiological and biochemical characteristics of cabbage plants were studied. The ability of the plants to take up Se and translocate it to different parts of the plants was also studied. Despite the high concentration of Se in the foliar solution, there was no effect on photosynthesis, transpiration rate, photochemical efficiency of PSII, or electron transport system activity. The amount of chlorophyll and anthocyanins were unchanged. At harvest, the concentration of Se in control plants was lower than 100 ng Se g^?1 dry weight (DW), while plants treated with 20 mg Se L^?1 contained 5500 ng Se g^?1. Selenium enriched cabbage could be used in human nutrition. The tolerance of cabbage to Se could be explained by the formation of insoluble compounds that are not available for the plant.     

Respiration und Freigabe von Aethylen in Beziehung zu den verschiedenen Entwicklungsphasen der Knollenbildung bei Kartoffeln

Zusammenfassung Die Geschwindigkeit der Respiration, die Freisetzung an Aethylen sowie die Gewichtszunahme an Knollen wurde w?hrend der Vegetation in der Zeit von Juni bis Oktober bei drei Kartoffelsorten (Resy, Karin, Kamyk) unter gleichen Anbaubedingungen geprüft. Die Anfangsphase der Knollenbildung wird durch eine starke Erh?hung der Respirationsaktivit?t und Freisetzung von Aethylen charakterisiert. In der Phase der Hemmung der Wachstumsaktivit?t der Pflanze vermindert sich dann die St?rke der Respiration sowie die Menge an Aethylen, das Knollengewicht steigt weiter an. Die Reihenfolge des Maximums der Respiration und Freisetzung an Aethylen ist nicht gleich, d.h. das Maximum der Respiration wird bei der Sorte Kamyk erreicht. Demgegenüber liegt das Maximum der Freisetzung von Aethylen bei der Sorte Karin. Die H?he der Respiration und die Freisetzung von Aethylen in Beziehung zum Knollengewicht scheint sortenspezifisch zu sein.     

Eradication of potato viruses A and S by thermotherapy and sprout tip culture

Summary Potato viruses A and S have been eradicated from varietiesJara andRajka by applying thermotherapy combined with nutrient culture of excised sprout tips.     

Long-term effect of straw and farmyard manure on soil organic matter in field experiment in the Czech Republic

The effect of long-term (45 years) mineral and organic fertilization on soil organic matter (SOM) quantity (organic C and N content) and quality (hot-water-soluble C content, microbial biomass C content, hydrophobic organic components of SOM, soil enzyme activities) was determined in a field experiment established in Trutnov (North Bohemia, sandy loam, Eutric Cambisol). Six treatments were chosen for investigation: unfertilized control, mineral fertilization (NPK), straw N, farmyard manure (FYM) and straw and FYM completed with mineral NPK. Soil samples were taken from the arable layer (0–20 cm) in spring over the period of 2004–2010. The positive effect of FYM on the total organic C and N content, hot-water-soluble C content and hydrophobic organic components of SOM was more than 50% higher than that of straw and mineral N fertilization. Application of straw N increased microbial biomass C content in soil and generated invertase activity above the level of FYM. Hot-water-soluble C content, hydrophobic organic components of SOM and urease activity were positively correlated with total organic C and N content (R = 0.58–0.98; p < 0.05). Addition of mineral NPK to both the straw and FYM emphasized the effect of organic fertilization in most of monitored characteristics.     

A comparative study of the Barley yellow dwarf virus species PAV and PAS: distribution,accumulation and host resistance

This study investigated the distribution and characteristics of the Barley yellow dwarf virus (BYDV) species BYDV‐PAS, which was recently separated from BYDV‐PAV, the most commonly studied BYDV species. Throughout 3 years of experimental monitoring of BYDV incidence, PAS was the most frequently occurring species infecting cereals and grasses in the Czech Republic. Furthermore, Rhopalosiphum maidis and Metopolophium dirhodum were recorded as BYDV‐PAS vectors, even though M. dirhodum does not usually transmit BYDV‐PAV. In field experiments with barley and wheat, where virus accumulation, symptoms and effect on the yield were tested, BYDV‐PAV was more severe than PAS. Infection with the BYDV‐PAV isolate resulted in greater expression of symptoms and also in a greater reduction in plant height and grain weight per spike than BYDV‐PAS. In a sensitive cultivar of barley (Graciosa), the amount of viral RNA of BYDV‐PAV was also significantly higher than that of BYDV‐PAS. In a tolerant line (Wbon‐123), however, no such differences were found. In conclusion, although BYDV‐PAS seems to be dominant in the Czech Republic, BYDV‐PAV has the potential to cause more significant crop losses in barley and wheat.     

Comparison of two methods for field grow of puncture vine (Tribulus terrestris L.) in Slovakia

One of the most claimed aphrodisiac plant is puncture vine (Tribulus terrestris L.) known as ‘plant Viagra’. This herb, growing especially in South and East Europe, is used for pharmaceutical purposes, due to its content of furostanol saponins which have stimulant effects on natural testosterone levels. Puncture vine grows as a weed on sandy soils areas. A study aimed to the introduction of puncture vine into large cultivation scale was carried out. Two different methods of cultivation were compared and production of biomass and evaluation of the content of furostanol saponins were done. Transplantation of seedlings raised in the greenhouse into the open field was more effective for the production of high amount of biomass and active components than using plants that are directly sown. The transplantation of seedlings into open field is suitable for the puncture vine cultivation as it increases biomass production.     

Resistance mechanisms of wild tomato germplasm to infection of Oidium neolycopersici

Tomato powdery mildew (Oidium neolycopersici) is one of the most devastating diseases of cultivated tomatoes worldwide. Although the first epidemics were recorded more than 25 years ago many aspects of this host-pathogen interaction are still not well understood. Detailed morphological and molecular studies of the anamorphs confirmed that O. neolycopersici is phylogeneticaly close to Erysiphe aquilegiae var. ranunculi. Host range is rather broad, apart from Solanaceae hosts were found in the families Apocynaceae, Campanulaceae, Crassulaceae, Cistaceae, Cucurbitaceae, Linaceae, Malvaceae, Papaveraceae, Pedialiaceae, Scrophulariaceae, Valerianaceae a Violaceae. Non-host resistance within these families is not based on inhibition of formation of primary haustorium, however, on post-haustorial hypersensitive reponse and another type of non-hypersensitive resistance. Screening of wild Solanum species (previous Lycopersicon spp.) germplasm revealed valuable sources of resistance (S. habrochaites, S. pennellii, S. cheesmaniae, S. chilense, S. peruvianum). The main resistance mechanism was found to be a hypersensitive response (HR), in some cases followed by limited development of the pathogen. However, there is a broad variation in resistance response on the histological and cytological level. Interaction between many wild Solanum spp. and O. neolycopersici is race-specific, at least three races were differentiated. In some interspecific crosses (S. lycopersicum × S. habrochaites) adult plant resistance was observed. Biochemical studies focusing on production of reactive oxygen species (ROS) and peroxidase activity during infection of O. neolycopersici showed that production of ROS and activity of corresponding enzymes is related to activation of defence responses in genotypes of wild Solanum sect. Lycopersicon. The significance of nitric oxide (NO) in O. neolycopersici pathogenesis was supported by experiments with NO donors and scavengers. In moderately resistant genotype S. chmielewskii, treatment by heat stress caused slight deceleration of pathogen development, increased production of jasmonic acid (JA) and abscisic acid (ABA) and increased peroxidase activity in infected plants. The different degree of tomato resistance/susceptibility did not markedly change the rate and extent of photosynthetic response to O. neolycopersici; only minimal impairment of photosynthesis was found in both susceptible and moderately resistant genotypes during the first 9 days after inoculation. The accumulated evidence confirm a crucial role of localised increased production of ROS and reactive nitrogen species (RNS) in response to pathogen penetration into plant tissue and its involvement in the plant resistance responses including the initiation and progression of plant cell death in host wild Solanum species. Crucial points of further research are discussed.     

Involvement of kaempferol in the defence response of virus infected Arabidopsis thaliana

The roles of several phenolic compounds in plant defence response have been extensively studied, yet little is known about the role of flavonoids in plant-virus interaction. Quantitative and qualitative changes of selected phenolics in Arabidopsis thaliana induced by Cucumber mosaic virus containing satellite RNA (CMVsat) infection were analysed accompanied by plant hormone, chalcone synthase and pathogenesis-related gene expression analysis. Lower leaves of infected plants had a lower concentration of total phenolics compared to control plants. The concentration of kaempferol in upper leaves of all infected plants was significantly lower compared to control plants, while the expression of the chalcone synthase gene in those leaves was in most cases upregulated. All infected plants had a higher concentration of indole-3-acetic acid in lower leaves, which was accompanied with a lower concentration of kaempferol in upper leaves. Our research demonstrates a correlation between kaempferol and indole-3-acetic acid in response to CMVsat infection in Arabidopsis. We demonstrated two different metabolic patterns in infected plants suggesting the activation of two different defence responses. We also propose kaempferol to be an important part of the auxin-dependent defence response which limits systemic movement of CMVsat and that this defence response is activated prior to the well-known salicylic acid dependent defence response. Further research on kaempferol and its role in Arabidopsis-CMVsat interaction will improve our understanding on the role of flavonoids in plant defence.