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1.
ABSTRACT A leaf spot disease with unknown etiology has become more pronounced in spring and winter barley in Germany in recent years. The symptoms are similar to net blotch and Ramularia leaf spots, but the causal agents of these diseases are not identified. The symptom expression varied much on cultivars. Cultivars most affected by the disease of both spring and winter barley showed a significantly higher level of superoxide (O(2) ) production and lipid peroxidation (malondialdehyde), but a lower level of antioxidant potential expressed as superoxide dismutase (SOD) activity, catalase activity, and integral water-soluble antioxidant capacity (ACW) than insensitive cultivars. A high positive correlation between O(2) production and leaf spot development between ear emergence and milk ripeness was established in the most sensitive winter barley cv. Anoa (r(2) = 0.9622) and spring barley cv. Barke (r(2) = 0.9434). Leaf H(2)O(2) levels increased with the severity of leaf spots. The histochemical localization of O(2) and H(2)O(2) in the tissues adjacent to leaf spots indicated that these two active oxygen species (AOS) are involved in the formation of leaf spots. Reduction of symptom severity by applying strobilurin and azole fungicides was always associated with elevated SOD activity and ACW content and suppressed O(2) production. However, peroxidase activities were significantly higher in sensitive cultivars and in more severely affected tissues and decreased by applying fungicides. Thus, it is assumed that a possible genetic mechanism based on the imbalanced AOS metabolism contributes to formation of physiological leaf spots. 相似文献
2.
Photosynthesis, respiration, and transpiration were studied in different Abies alba provenances during and alter ozone exposure at three different levels (0/control, 125, and 250 ppb O3, respectively). The after-effects of ozone on frost resistance and growth rate were also analyzed. Pronounced reductions of photosynthesis and transpiration rates and an increased respiration were registered as a response to O3. Five months after exposure the winter frost resistance was significantly reduced, and growth depressions were registered during the following year. Differences in ozone sensibility and regeneration ability between provenances could be demonstrated. 相似文献
3.
ABSTRACT We reported previously that physiological leaf spot (PLS) formation in winter and spring barley is dependent on genotype-related oxidative stress under field conditions. In the present study, we searched for factors inducing PLS symptoms in the greenhouse similar to those observed in the field and investigated its relationship to reactive oxygen species (ROS) metabolism. We found that in the greenhouse, oxidative stress induced spring barley cv. Extract, which is sensitive to PLS, to express symptoms similar to those observed in the field. Leaves severely affected by PLS showed significantly lower activities of key enzymes in the Halliwell-Asada cycle such as ascorbate peroxidase, glutathione reductase, dehy-droascorbate reductase, and monodehydroascorbate reductase. The sensitive cultivar also showed lower levels of total superoxide dismutase (SOD) and Cu/Zn-SOD activity but a higher level of chloroplast-specific Fe-SOD activity than that of the insensitive cultivar. Thus, an unbalanced ROS metabolism in chloroplasts may trigger PLS incidence in sensitive cultivars, which is in agreement with the fact that light is essential for the induction of PLS expression under both field and greenhouse conditions. Accordingly, under greenhouse conditions, continuous light stress (7 days), but not light shock treatments, induced PLS similar to that of field conditions in sensitive cv. Extract, but not in resistant cv. Scarlett. Light with a high proportion of energy in the blue wavelength spectrum (350 to 560 nm) was significantly more PLS inductive than light with a pronounced red (photosynthetically active radiation) spectrum (580 to 650 nm). Exposure to ozone did not produce PLS-like symptoms. Furthermore, similar to earlier observations in the field, PLS symptom expression was closely correlated with the accumulation of superoxide (O(2) (-)) detected by both biochemical and histochemical assays. Taken together, these data suggest that PLS in barley is genotype-dependent but its expression appears to be induced by certain environmental stress factors, among which photosyn-thetically active radiation plays a major role. 相似文献
4.
KW Berendzen M Böhmer N Wallmeroth S Peter M Vesi Y Zhou FK Tiesler F Schleifenbaum K Harter 《Plant methods》2012,8(1):25-17
ABSTRACT: Understanding protein and gene function requires identifying interaction partners usingbiochemical, molecular or genetic tools. In plants, searching for novel protein-proteininteractions is limited to protein purification assays, heterologous in vivo systems such as the yeast-two-hybrid or mutant screens. Ideally one would be able to search for novel proteinpartners in living plant cells. We demonstrate that it is possible to screen for novel proteinproteininteractions from a random library in protoplasted Arabidopsis plant cells and recoversome of the interacting partners. Our screen is based on capturing the bi-molecularcomplementation of mYFP between an YN-bait fusion partner and a completely random preyYC-cDNA library with FACS. The candidate interactions were confirmed using in plantaBiFC assays and in planta FRET-FLIM assays. From this work, we show that the wellcharacterized protein Calcium Dependent Protein Kinase 3 (CPK3) interacts with APX3,HMGB5, ORP2A and a ricin B-related lectin domain containing protein At2g39050. This isone of the first random in planta screens to be successfully employed. 相似文献
5.
Efficient plant protection is of fundamental importance in order to warrant food security. Here, we present arguments that a coordinate approach in plant protection is urgently required, taking advantage of a broad mix of measures, including modern synthetic chemistries, capable of protecting plants from adverse organisms.
相似文献6.
7.
Thomas Littmann Maik Veste 《中国林学(英文版)》2005,7(4):24-28
A stochastic numerical approach was developed to model the actual standing biomass in the sand dunes of the northwestern Negev （Israel） and probable boundary conditions that may be responsible for the vegetation patterns investigated in detail. Our results for several variables characteristic for the prevailing climate, geomorphology, hydrology and biologicy at four measurement stations along a transect from northwest to southeast allowed for the development of a stochastic model for biomass distribution over the entire sand dune field （mesoscale） and at Nizzana experimental station （microscale）. With this equation it was possible to compute and interpolate a biomass index value for each grid point on the mesoscale and micro scale. The spatial distribution of biomass is negatively linked to distance from the sea, to rainfall and relief energy. 相似文献
8.
Aklilu W Alemu Adam L Shreck Calvin W Booker Sean M McGinn Liana K D Pekrul Maik Kindermann Karen A Beauchemin 《Journal of animal science》2021,99(1)
The present study evaluated enteric CH4 production, dry matter (DM) intake (DMI), and rumen fermentation in feedlot cattle supplemented with increasing concentrations of 3-nitrooxypropanol (3-NOP). A total of 100 crossbred steers (body weight, 421 ± 11 kg) was randomly assigned to one of four treatments (n = 25/treatment): control (no 3-NOP) or low (100 mg/kg DM), medium (125 mg/kg DM), and high (150 mg/kg DM) doses of 3-NOP. The study was comprised of 28 d of adaptation followed by three 28-d periods, with CH4 measured for 7 d per period and cattle remaining on their respective diets throughout the 112-d study. Each treatment group was assigned to a pen, with the cattle and diets rotated among pens weekly to allow the animals to access the GreenFeed emission monitoring (GEM) system stationed in one of the pens for CH4 measurement. Measured concentration (mg/kg DM) of 3-NOP in the total diet consumed (basal diet + GEM pellet) was 85.6 for low, 107.6 for medium, and 124.5 for high doses of 3-NOP. There was a treatment × period interaction (P < 0.001) for DMI; compared with control, the DMI was less for the low and high doses in period 1, with no differences thereafter. Compared with control (10.78 g/kg DMI), CH4 yield (g/kg DMI) was decreased (P < 0.001) by 52%, 76%, and 63% for low, medium, and high doses of 3-NOP, respectively. A treatment × period effect (P = 0.048) for CH4 yield indicated that the low dose decreased in efficacy from 59% decrease in periods 1 and 2 to 37% decrease in period 3, while the efficacy of the medium and high doses remained consistent over time. Irrespective of dose, hydrogen emissions increased by 4.9-fold (P < 0.001), and acetate:propionate ratio in rumen fluid decreased (P = 0.045) with 3-NOP supplementation, confirming that other hydrogen-utilizing pathways become more important in the CH4-inhibited rumen. The study indicates that supplementation of corn-based finishing diets with 3-NOP using a medium dose is an effective CH4 mitigation strategy for commercial beef feedlots with a 76% decrease in CH4 yield. Further research is needed to determine the effects of 3-NOP dose on weight gain, feed conversion efficiency, and carcass characteristics of feedlot cattle at a commercial scale. 相似文献
9.
Water repellency and pore clogging at early successional stages of microbiotic crusts on inland dunes,Brandenburg, NE Germany 总被引：2，自引：0，他引：2
Biological soil crusts play a key role for hydrological processes in many open landscapes. They seal the topsoil and generate surface run-off. Utilization of the mineral substrate at early stages of microbiotic crusts was investigated using scanning electron microscopy (SEM), water repellency indices were measured using the ethanol/water microinfiltrometer method, and steady state water flow was determined on the dry crusts and after 300, 600, 1200 and 1800 s of wetting, thus allowing to follow pore clogging through swelling of extracellular polymeric substances (EPS). It was found that water repellency increases with initial crust development where filamentous cyanobacteria and filamentous green algae were dominating, but decreases as coccal algae, bryophytes and fungi associated with bryophytes emerged. Swelling of EPS took place immediately after wetting, and its influence on steady state water flow was most pronounced when filamentous cyanobacteria and algae partially filled in the matrix pores and enmeshed sand grains, still leaving micropore channels available for free water infiltration, but prior to appearance of coccal algae, bryophytes and associated fungi which formed a dense cover on the surface. It was concluded that a new phase of crust succession was accompanied by easier wettability but slower infiltration. Transition from hydrophobicity to pore clogging as ruling mechanisms causing water run-off may occur during wetting of individual biological crusts, but also during crust succession over time. 相似文献
10.
Radiographs of cats at known stages of gestation reveal that it is possible in some cases to diagnose pregnancy as early as the 17th day. In all cases examined this was possible by the 21st day. A diagram is presented in which the short width of the uterine embryonic swellings measured from radiographs is compared with swellings measured on uteri taken from cats sacrificed between day 17 and day 30 of pregnancy. The diagram may be used for the approximate determination of the stage of pregnancy in cases where mating time is unknown. Résumé. Des radiographies de chats à des stades connus de gestation révèlent qu'il est possible, dans certains cas, de diagnostiquer une grossesse dès le 17ième jour. Dans tous les cas examinés, cela était possible vers le 21 ième jour. On présente un diagramme dans lequel la petite largeur des renflements utérins embryonnaires mesurés d'après des radiographies est comparée avec des renflements sur des utérus pris de chats sacrifiés entre le 17ième et le 30ième jour de grossesse. Le diagramme peut ětre utilisé pour déterminer approximativement le stade de grossesse dans des cas où le moment de conception n'est pas connu. Zusammenfassung. Rǒntgenaufnahmen von Katzen an uns bekannten Zeitpunkten von Gestation zeigten, dass es in einigen Fàllen mǒglich ist Schwangerschaft so frùh wie am 17ten Tag zu diagnostizieren. In allen untersuchten Fǎllen war dièses am 21ten Tag mǒglich. Eine graphische Darstellung wurde gezeigt, in welcher die kurze Breite der utérine Embryo-Schwellung, die man in den Rǒntgenaufnahmenmass, mit den Schwellungen an Uteri verglich welche man von Katzen entfernte, die zwischen dem 17. und 30. Tag des Schwangerschaft getǒtet wurden. Die Darstellung kann fur die ungefàhre Bestimmung von Zeitpunkt der Schwangerschaft gebraucht werden, in Fǎllen wo man nicht weiss, wann Paarung stattfand. 相似文献