Common ragweed (Ambrosia artemisiifolia L.) causes severe yield losses in different soybean varieties by reducing the infection potential of Bradyrhizobium japonicum

Das ursprünglich aus Nordamerika stammende Ragweed oder Beifuß-Ambrosia (Ambrosia artemisiifolia L. (Asteraceae), íst eine einjährige, krautige Pflanze. Sie hat sich in den letzten Jahrzehnten massiv ausgebreitet und zählt heute in vielen Teilen Mitteleuropas zu den wirtschaftlich wichtigsten Unkrautarten in der Landwirtschaft. Aktuell übliche Bekämpfungsmaßnahmen wie Mähen oder Herbizidapplikationen zeigen auf vielen Standorten nur sehr eingeschränkte Erfolge, sind aus zeitlichen oder wirtschaftlichen Gründen nicht umsetzbar bzw. scheitern daran, dass der Neophyt nicht erkannt wird. Speziell Sojabohnenbestände wurden in den letzten Jahren immer stärker von Ragweed befallen, jedoch gibt es bislang nur wenige Studien zur Ertragswirkung von Ragweed. Das Ziel des zweijährigen Feld- und einjährigen Glashausversuches, die 2017 und 2018 durchgeführt wurden, war deshalb die Untersuchung der Konkurrenzeffekte von Ragweed auf 1) Wachstum (oberirdisch / unterirdisch), 2) Entwicklung, 3) Infektionspotential der Knöllchenbakterien und 4) Ertrag von zwei verschiedenen Sojabohnensorten. Die Ergebnisse der Untersuchung zeigten, dass auf den Versuchsflächen mit der höchsten Ragweed-Biomasse der Sojaertrag um 83,7 % sank. Speziell die Anzahl und das Gewicht der Knöllchen (Bradyrhizobium japonicum) auf den Sojawurzeln wurden durch Anwesenheit von Ragweed stark reduziert. Eine Ragweed-Pflanze pro Quadratmeter reichte aus, um die Anzahl der Knöllchen um durchschnittlich 55,8 % zu reduzieren. Da jedoch eine effektive Infektion wesentlich zur Ertragsbildung von Soja beiträgt, führte diese Reduktion an Knöllchenbakterien bzw. deren Gewicht zu einem Ertragsverlust von 18 %.Ambrosia artemisiifolia L. (Asteraceae) known as common ragweed is an annual herbaceous species native to North America which has become one of the economically most important weeds in agricultural areas throughout Middle Europe. Its large ecological amplitude enables the species to establish in several types of environment, but management options to effectively contain its spread are limited due to lack of efficacy, cost and time or lack of awareness. In the last decade especially soybean fields were severely affected by ragweed invasion, but until now information on the yield-decreasing effects of the plant are scarce for Middle Europe. Therefore, the aim of the study, conducted in 2017 and 2018 as a greenhouse and biennial field trial, was an evaluation of the competition effects of ragweed upon 1) growth (aboveground/belowground), 2) infection potential of rhizobia and 3) yield of two different soybean varieties. Results revealed that on plots with the highest ragweed biomass the yield loss accounted for 83.7% on average. Particularly, the numbers of nodules as well as the mean weight of the nodule, which stand in tight correlation with soybean yield, were significantly reduced by the presence of ragweed. Only one ragweed plant per square metre reduced the number of nodules by 55.8% and consequently led to a decrease in yield of 18%

Know your enemy: Are biochemical substances the secret weapon of common ragweed (Ambrosia artemisiifolia L.) in the fierce competition with crops and native weeds?

Entsprechend der „Novel Weapon“-Hypothese, kann der Invasionserfolg von nicht-heimischen Arten wie Ragweed (Ambrosia artemisiifolia L.) auf einen Verlust von natürlichen Konkurrenten zurückzuführen sein. Grund für diesen Verlust sind chemische Verbindungen, die die gebietsfremde Art erzeugt und die heimische Arten aufgrund fehlender Koevolution negativ beeinträchtigen. Studien haben gezeigt, dass die Gattung Ambrosia unterschiedliche organische Verbindungen produziert, von denen sehr viele ein breites Spektrum an biologischer Aktivität zeigen, weshalb diese chemischen Verbindungen ein wichtiger Grund für den Invasionserfolg und die Konkurrenzkraft der Pflanze sein können. Um 1) das chemische Profil der oberirdischen Biomasse offenzulegen, wurden vier verschiedene Extrakte (wässriger Extrakt, Hexan-Extrakt, Methanol-Extrakt und ätherisches Öl) hergestellt und auf ihre Inhaltsstoffe analysiert. Im nächsten Schritt wurde ein Laborexperiment durchgeführt, dass Aufschluss darüber geben sollte 2) welche Effekte unterschiedliche Konzentrationen dieser Extrakte auf Keimung und Jungpflanzenentwicklung von drei verschiedenen Kulturpflanzen (Sojabohne, Weizen und Raps), drei heimischen Unkrautarten (Chenopodium album, Senecio vulgaris und Arabidopsis thaliana) sowie auf Ragweed selbst, haben. Die Ergebnisse zeigten, eine deutliche Beeinträchtigung von Keimung und Entwicklung aller getesteten Pflanzenarten. Obwohl keiner der Extrakte eine direkte Wirkung auf die Keimfähigkeit der Kulturpflanzen hatte, konnte eine deutliche Wachstumsreduktion von Wurzel und Spross bei allen Nutzpflanzen festgestellt werden. Im Gegensatz dazu, konnte man bei den heimischen Unkrautarten und Ragweed selbst eine deutlich verminderte Keimfähigkeit sowie Wachstumshemmung speziell bei der Behandlung mit ätherischem Öl und dem wässrigen Extrakt beobachten.Following the “novel weapon hypothesis”, the invasiveness of non-native species like common ragweed (Ambrosia artemisiifolia L.) can result from a loss of natural competitors due to the production of chemical compounds by the non-native species that unfavorably affect native communities. In this case, native plants may not be able to tolerate compounds released by a non-native plant that has not co-evolved in the same environment. Particularly the genus Ambrosia produces several types of organic compounds, which have a broad spectrum of biological activities and which could be major drivers in the successful invasion and competition process of common ragweed. To 1) asses the chemical profile of the aboveground biomass of common ragweed four different extracts (H2O, hexane extract, methanol extract and essential oil) were prepared and analysed for their content substances. In the next step a laboratory experiment was implemented to 2) determine the effects of different concentrations of these substances on germination and seedling development of three different crops (soybean, wheat, and rapeseed), native weedy species (Chenopodium album, Senecio vulgaris and Arabidopsis thaliana) and on common ragweed itself. Results showed that germination as well as seedling development was significantly influenced by the chemical compounds in the extracts. Even though the extracts did not affect the germination capacity of crops, severe reduction in root and shoot growth were observed with all three tested crops. The highest inhibitory effect on germination of native weedy species as well as common ragweed was observed with essential oil and the aqueous extract

In vivo sun protection factor and UVA protection factor determination using (hybrid) diffuse reflectance spectroscopy and a multi‐lambda‐LED light source

The sun protection factor (SPF) values are currently determined using an invasive procedure, in which the volunteers are irradiated with ultraviolet (UV) light. Non-invasive approaches based on hybrid diffuse reflectance spectroscopy (HDRS) have shown a good correlation with conventional SPF testing. Here, we present a novel compact and adjustable DRS test system. The in vivo measurements were performed using a multi-lambda-LED light source and an 84-channel imaging spectrograph with a fiber optic probe for detection. A transmission spectrum was calculated based on the reflectance measured with sunscreen and the reflectance measured without sunscreen. The preexposure in vitro spectrum was fitted to the in vivo spectrum. Each of the 11 test products was investigated on 10 volunteers. The SPF and UVA-PF values obtained by this new approach were compared with in vivo SPF results determined by certified test institutes. A correlation coefficient R-2 = 0.86 for SPF, and R-2 = 0.92 for UVA-PF were calculated. Having examined various approaches to apply the HDRS principle, the method we present was found to produce valid and reproducible results, suggesting that the multi-lambda-LED device is suitable for in-vivo SPF testing based on the HDRS principle as well as for in-vivo UVA-PF measurements

Noninvasive measurement of the 308 nm LED‐based UVB protection factor of sunscreens

The current method for determining the sun protection factor (SPF) requires erythema formation. Noninvasive alternatives have recently been suggested by several groups. Our group previously developed a functional sensor based on diffuse reflectance measurements with one UVB LED, which was previously evaluated on pig ear skin. Here we present the results of a systematic in vivo study using 12 sunscreens on 10 volunteers (skin types [ST] I-III). The relationship of the UVB-LED reflectance of unprotected skin and melanin index was determined for each ST. The spatial variation of the reflectance signal of different positions was analyzed and seems to be mainly influenced by sample inhomogeneity except for high-protection factors (PFs) where signal levels are close to detection noise. Despite the low-signal levels, a correlation of the measured LED-based UVB PF with SPF reference values from test institutes with R-2 = 0.57 is obtained, suggesting a strong relationship of SPF and LED-based UVB-PF. Measured PFs tend to be lower for increasing skin pigmentation. The sensor design seems to be suitable for investigations where a fast measurement of relative changes of PFs, such as due to inhomogeneous application, bathing and sweating, is of interest

Degree of Actinic Elastosis Is a Surrogate of Exposure to Chronic Ultraviolet Radiation and Correlates More Strongly with Cutaneous Squamous Cell Carcinoma than Basal Cell Carcinoma

(1) Background: Keratinocyte cancer (KC) is associated with exposure to ultraviolet (UV) radiation. However, data are controversial as to whether chronic UV exposure or high intermittent UV exposure are key drivers of carcinogenesis in cutaneous squamous cell carcinoma (cSCC) and basal cell carcinoma (BCC). Prolonged sun exposure of the skin causes photo-aging, which is associated with actinic elastosis, a condition characterized by the degeneration of elastin in the upper dermis, which is assessable via conventional histology. In this study, we aimed to compare the degree of actinic elastosis in different types of KC with regard to various patient characteristics. (2) Methods: We defined a semiquantitative score for the degree of actinic elastosis ranging from 0 = none to 3 = total loss of elastic fibers (basophilic degeneration). The extent was measured histometrically by two independent dermatohistopathologists in the immediate vicinity of 353 KC. The scores were merged and matched with tumor types (cSCC and BCC with subtypes), and clinical variables such as body site, sex and age. (3) Results: As expected, the degree of actinic elastosis correlated with age. However, it was significantly higher in cSCC compared to BCC irrespective of age, sex, body site and tumor subtypes. (4): Conclusions: Lifetime sun exposure may be estimated via routine histology using this scoring technique for actinic elastosis as a surrogate marker. cSCCs are more strongly associated with chronic UV exposure than BCCs, even in sun-exposed localizations such as the face

Multiple immune abnormalities in tumor necrosis factor and lymphotoxin-α double-deficient mice

To investigate the roles of tumor necrosis factor (TNF) and lymphotoxin (LT)-α in the development and function of the immune system, the Tnf and Ltα genes were simultaneously inactivated in mice by homologous recombination. These mutant mice are highly susceptible to Listeria monocytogenes infection and resistant to endotoxic shock induced by the combined administration of D-galactosamine (D-GaIN) and lipopolysaccharide (LPS). Their splenic microarchitecture is disorganized, characterized by the loss of the clearly defined marginal zone, ill defined T and B cell areas, and absence of MAdCAM-1 and reduced ICAM-1, VCAM-1 and Mac-1 expression. They are devoid of peripheral lymph nodes and Peyer's patches, and show a strong reduction of lgA+ plasma cells in the intestinal lamina propria. The alymphoplasia is accompanied by a marked B lymphocytosis and reduced basal Ig levels. Ig depositions in the renal glomerulus and a strong up-regulation of MHC class I antigen expression on endothelial cells of different tissues are observed. The primary humoral immune response towards sheep red blood cells reveals a defective IgG isotype switch, while that against vescicular stomatitis virus is normal. The cytotoxic T cell responses are attenuated, although still effective, against vaccinia, lymphocytic choriomeningitis virus (LCMV-ARM) and LCMV-WE. In conclusion, the combined inactivation of Tnf and Ltα confirms their essential role in the normal development and function of the immune syste

Significance of Cuscutain, a cysteine protease from Cuscuta reflexa, in host-parasite interactions

<p>Abstract</p> <p>Background</p> <p>Plant infestation with parasitic weeds like <it>Cuscuta reflexa </it>induces morphological as well as biochemical changes in the host and the parasite. These modifications could be caused by a change in protein or gene activity. Using a comparative macroarray approach <it>Cuscuta </it>genes specifically upregulated at the host attachment site were identified.</p> <p>Results</p> <p>One of the infestation specific <it>Cuscuta </it>genes encodes a cysteine protease. The protein and its intrinsic inhibitory peptide were heterologously expressed, purified and biochemically characterized. The haustoria specific enzyme was named cuscutain in accordance with similar proteins from other plants, e.g. papaya. The role of cuscutain and its inhibitor during the host parasite interaction was studied by external application of an inhibitor suspension, which induced a significant reduction of successful infection events.</p> <p>Conclusions</p> <p>The study provides new information about molecular events during the parasitic plant - host interaction. Inhibition of cuscutain cysteine proteinase could provide means for antagonizing parasitic plants.</p

Rückblick auf die Soziologie Vilfredo Paretos

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