Pollination in flowering plants is initiated by germination of pollen grains on stigmas followed by fast growth of pollen tubes representing highly energy-consuming processes. The symplastic ...isolation of pollen grains and tubes requires import of Suc available in the apoplast. We show that the functional coupling of Suc cleavage by invertases and uptake of the released hexoses by monosaccharide transporters are critical for pollination in tobacco (Nicotiana tabacum). Transcript profiling, in situ hybridization, and immunolocalization of extracellular invertases and two monosaccharide transporters in vitro and in vivo support the functional coupling in supplying carbohydrates for pollen germination and tube growth evidenced by spatiotemporally coordinated expression. Detection of vacuolar invertases in maternal tissues by these approaches revealed metabolic cross talk between male and female tissues and supported the requirement for carbohydrate supply in transmitting tissue during pollination. Tissue-specific expression of an invertase inhibitor and addition of the chemical invertase inhibitor miglitol strongly reduced extracellular invertase activity and impaired pollen germination. Measurements of (competitive) uptake of labeled sugars identified two import pathways for exogenously available Suc into the germinating pollen operating in parallel: direct Suc uptake and via the hexoses after cleavage by extracellular invertase. Reduction of extracellular invertase activity in pollen decreases Suc uptake and severely compromises pollen germination. We further demonstrate that Glc as sole carbon source is sufficient for pollen germination, whereas Suc is supporting tube growth, revealing an important regulatory role of both the invertase substrate and products contributing to a potential metabolic and signaling-based multilayer regulation of pollination by carbohydrates.
Electret filters are widely used in HVAC systems to decrease particulate matter in indoor environments. The previous standard in Europe for testing air filters for general ventilation was EN 779. In ...July 2018, it was replaced by the new international standard ISO 16890. One major change is the discharging process: It is now performed by treating the filters with saturated isopropyl alcohol (IPA) vapor. The process is intended to simulate a worst‐case scenario of the filtration efficiency due to the reduction of the electret effect. These minimal efficiencies are a principal part of the filter classification. Therefore, two round robin tests with different filter classes (F9 and F7 according to EN 779) and up to eleven participants were carried out to evaluate the new test method by comparing the filtration efficiencies and pressure drops before and after the IPA treatment. Pressure drop measurements showed no mechanical altering of the material due to the discharging process. The calculated filter classes had a maximum deviation of 5%. Even with different equipment, the results indicate that the new ISO 16890 seems to be a viable test standard and a decent replacement for previous national standards.
Cytokinins are phytohormones that are involved in various regulatory processes throughout plant development, but they are also produced by pathogens and known to modulate plant immunity. A novel ...transgenic approach enabling autoregulated cytokinin synthesis in response to pathogen infection showed that cytokinins mediate enhanced resistance against the virulent hemibiotrophic pathogen Pseudomonas syringae pv tabaci. This was confirmed by two additional independent transgenic approaches to increase endogenous cytokinin production and by exogenous supply of adenine-and phenylurea-derived cytokinins. The cytokinin-mediated resistance strongly correlated with an increased level of bactericidal activities and up-regulated synthesis of the two major antimicrobial phytoalexins in tobacco (Nicotiana tahacum), scopoletin and capsidiol. The key role of these phytoalexins in the underlying mechanism was functionally proven by the finding that scopoletin and capsidiol substitute in planta for the cytokinin signal: phytoalexin pretreatment increased resistance against P. syringae. In contrast to a cytokinin defense mechanism in Arabidopsis {Arabidopsis thaliana) based on salicylic acid-dependent transcriptional control, the cytokininmediated resistance in tobacco is essentially independent from salicylic acid and differs in pathogen specificity. It is also independent of jasmonate levels, reactive oxygen species, and high sugar resistance. The novel function of cytokinins in the primary defense response of solanaceous plant species is rather mediated through a high phytoalexin-pathogen ratio in the early phase of infection, which efficiently restricts pathogen growth. The implications of this mechanism for the coevolution of host plants and cytokinin-producing pathogens and the practical application in agriculture are discussed.
Filtermedien der Filterklasse E12 wurden im Labor mit NaCl‐Partikeln und Feuchte beaufschlagt und anschließend einer DEHS‐Effizienzmessung (DEHS: Di‐Ethyl‐Hexyl‐Sebacat) in Anlehnung an DIN EN 1822 ...Teil 3 unterzogen. Verglichen wurden Druckverluste und Fraktionsabscheidegrade in unterschiedlichen Beladungsstadien mit Ergebnissen des Ausgangszustands, um die Relevanz von Feuchte oder wasserlöslichen Verunreinigungen wie Salz auf die Filtrationsleistung zu erfassen. Im Anschluss wurden Aufnahmen mit einem Raster‐Elektronen‐Mikroskop gemacht, um ein besseres Verständnis für das Verhalten der abgeschiedenen Partikel in den unterschiedlichen Beladungsstadien zu erlangen. Die Ergebnisse werden mit Filtern aus dem Realbetrieb verglichen.
Filter media of E12 filters were exposed to NaCl particles and high relative humidity. Afterwards the particle separation efficiency of DEHS (DEHS: di(2‐ethylhexyl) sebacate) and pressure drop were measured according to DIN EN 1822 part 3. The results of new filter media and those at different loadings were compared to determine the influence of relative humidity or water‐soluble impurities like salt. In addition, scanning electron microscope pictures were taken to achieve a better understanding of the particle behavior inside the filters. The results are compared to filter media aged in real applications.
In Anlehnung an DIN EN 1822 Teil 3 wurden Filtermedien einer DEHS‐Effizienzmessung unterzogen, nachdem sie zuvor mit NaCl‐Partikeln und Feuchte beaufschlagt wurden. Der Vergleich sowohl mit dem Neuzustand als auch mit Filtern aus dem Realbetrieb zeigte deutliche Diskrepanzen. Zusätzlich wurden Raster‐Elektronen‐Mikroskop‐Aufnahmen ausgewertet.
Abstract
Filtermedien der Filterklasse E12 wurden im Labor mit NaCl‐Partikeln und Feuchte beaufschlagt und anschließend einer DEHS‐Effizienzmessung (DEHS: Di‐Ethyl‐Hexyl‐Sebacat) in Anlehnung an DIN ...EN 1822 Teil 3 unterzogen. Verglichen wurden Druckverluste und Fraktionsabscheidegrade in unterschiedlichen Beladungsstadien mit Ergebnissen des Ausgangszustands, um die Relevanz von Feuchte oder wasserlöslichen Verunreinigungen wie Salz auf die Filtrationsleistung zu erfassen. Im Anschluss wurden Aufnahmen mit einem Raster‐Elektronen‐Mikroskop gemacht, um ein besseres Verständnis für das Verhalten der abgeschiedenen Partikel in den unterschiedlichen Beladungsstadien zu erlangen. Die Ergebnisse werden mit Filtern aus dem Realbetrieb verglichen.
Abstract
Filter media of E12 filters were exposed to NaCl particles and high relative humidity. Afterwards the particle separation efficiency of DEHS (DEHS: di(2‐ethylhexyl) sebacate) and pressure drop were measured according to DIN EN 1822 part 3. The results of new filter media and those at different loadings were compared to determine the influence of relative humidity or water‐soluble impurities like salt. In addition, scanning electron microscope pictures were taken to achieve a better understanding of the particle behavior inside the filters. The results are compared to filter media aged in real applications.
Invertases and hexose transporters, as essential components of carbohydrate supply, are regulated in a spatiotemporally coordinated manner to maintain functionality of tobacco pollination.
...Pollination in flowering plants is initiated by germination of pollen grains on stigmas followed by fast growth of pollen tubes representing highly energy-consuming processes. The symplastic isolation of pollen grains and tubes requires import of Suc available in the apoplast. We show that the functional coupling of Suc cleavage by invertases and uptake of the released hexoses by monosaccharide transporters are critical for pollination in tobacco (
Nicotiana tabacum
). Transcript profiling, in situ hybridization, and immunolocalization of extracellular invertases and two monosaccharide transporters in vitro and in vivo support the functional coupling in supplying carbohydrates for pollen germination and tube growth evidenced by spatiotemporally coordinated expression. Detection of vacuolar invertases in maternal tissues by these approaches revealed metabolic cross talk between male and female tissues and supported the requirement for carbohydrate supply in transmitting tissue during pollination. Tissue-specific expression of an invertase inhibitor and addition of the chemical invertase inhibitor miglitol strongly reduced extracellular invertase activity and impaired pollen germination. Measurements of (competitive) uptake of labeled sugars identified two import pathways for exogenously available Suc into the germinating pollen operating in parallel: direct Suc uptake and via the hexoses after cleavage by extracellular invertase. Reduction of extracellular invertase activity in pollen decreases Suc uptake and severely compromises pollen germination. We further demonstrate that Glc as sole carbon source is sufficient for pollen germination, whereas Suc is supporting tube growth, revealing an important regulatory role of both the invertase substrate and products contributing to a potential metabolic and signaling-based multilayer regulation of pollination by carbohydrates.
Male sterility is of special interest as a mechanism allowing hybrid breeding, especially in important crops such as rapeseed (Brassica napus). Male sterile plants are also suggested to be used as a ...biological safety method to prevent the spread of transgenes, a risk that is high in the case of rapeseed due to the mode of pollination, out-crossing by wind or insects, and the presence of related, cross-pollinating species in the surrounding ecosystem in Europe. Different natural occurring male sterilities and alloplasmic forms have been tried to be used in rapeseed with more or less success. Due to the difficulties and limitations with these systems, we present a biotechnological alternative: a metabolically engineered male sterility caused by interference with anther-specific cell wall-bound invertase. This is an essential enzyme for carbohydrate supply of the symplastically isolated pollen. The activity of this enzyme is reduced either by antisense interference or by expressing an invertase inhibitor under control of the anther-specific promoter of the invertase with the consequence of a strong decrease of pollen germination ability.
Cytokinins are phytohormones that are involved in various regulatory processes throughout plant development, but they are also produced by pathogens and known to modulate plant immunity. A novel ...transgenic approach enabling autoregulated cytokinin synthesis in response to pathogen infection showed that cytokinins mediate enhanced resistance against the virulent hemibiotrophic pathogen Pseudomonas syringae pv tabaci. This was confirmed by two additional independent transgenic approaches to increase endogenous cytokinin production and by exogenous supply of adenine- and phenylurea-derived cytokinins. The cytokinin-mediated resistance strongly correlated with an increased level of bactericidal activities and up-regulated synthesis of the two major antimicrobial phytoalexins in tobacco (Nicotiana tabacum), scopoletin and capsidiol. The key role of these phytoalexins in the underlying mechanism was functionally proven by the finding that scopoletin and capsidiol substitute in planta for the cytokinin signal: phytoalexin pretreatment increased resistance against P. syringae. In contrast to a cytokinin defense mechanism in Arabidopsis (Arabidopsis thaliana) based on salicylic acid-dependent transcriptional control, the cytokinin-mediated resistance in tobacco is essentially independent from salicylic acid and differs in pathogen specificity. It is also independent of jasmonate levels, reactive oxygen species, and high sugar resistance. The novel function of cytokinins in the primary defense response of solanaceous plant species is rather mediated through a high phytoalexin-pathogen ratio in the early phase of infection, which efficiently restricts pathogen growth. The implications of this mechanism for the coevolution of host plants and cytokinin-producing pathogens and the practical application in agriculture are discussed.
The complete coding and 3´-flanking region of the mitochondrial gene atp9 of chives (Allium schoenoprasum L.) was determined in order to develop primers that allow the identification of atp9-related ...sequences in subsequent PCR-amplifications. One of these sequences is of a chimerical nature, consisting of atp9-homologous regions on its end, interrupted by an insertion that is composed of one atp6-homologous part and one part of unknown origin. This PCR-fragment is 762 bp in size and exclusively amplified in the sterility inducing cytoplasm of CMS^sub 1^. Thus it can be used as a PCR-marker in order to distinguish this cytoplasm type from the remaining cytoplasm types of chives. The chimerical marker sequence forms a putative open reading frame (orfA501), from which CMS^sub 1^ might originate.PUBLICATION ABSTRACT
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