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Do different host species and distinct habitats alter the olfactory host search of the ectoparasitoid Holepyris sylvanidis?
Get PDFStories from One Thousand and Two Secale Samples: Insights into the evolutionary history of domesticated rye and its wild relatives
Get PDFSeasonal and yearly variation of total polyphenols, total anthocyanins and ellagic acid in different clones of cloudberry (Rubus chamaemorus L.)
Get PDFCloudberry (Rubus chamaemorus L.) is a wild perennial shrub growing on peatland with a circumpolar distribution. The combined berries have a high polyphenol content comprised primarily of ellagitannins. A few commercial cultivars are available, and pre-breeding trials on clonal material from different geographical origins are in progress. The objective of this study was to investigate how the content of polyphenols of four different cloudberry cultivars were affected by harvesting time and climatic variations during a 3-year-period. Plants were grown outside in plots and berries were harvested when mature. Berries were analyzed for total polyphenols and total anthocyanins by spectrophotometer. Total ellagic acid was identified and quantified using HPLC-MS after hydrolysis of the extracts. Results showed that all measured parameters; total anthocyanins, total polyphenols and ellagic acid are strongly influenced by the genetic background. Although low anthocyanin contents were present in all genotypes, they were highly affected by climatic conditions, being highest at low temperatures. However, the content of ellagic acid was less affected by environmental conditions and showed little response to changing temperatures. In conclusion, ellagitannin content was the most dominating polyphenol group observed in this study and was affected by genetics and is therefore a good breeding criterion for increased health benefit of cloudberry
Interaction of the Beet necrotic yellow vein virus with the auxin signaling pathway in sugar beet
Get PDFApplication of next-generation sequencing for simultaneous detection of viruses, viroids and phytoplasmas in grapevine & fruit trees
Get PDFGenome wide association studies for resistance of wheat to the root lesion nematode Pratylenchus neglectus
Get PDFFactors influencing the fate of Salmonella in the plant and soil environment
No full textFrisches Obst und Gemüse sind Teil einer gesunden Ernährung. Jedoch können diese Frischeprodukte, wenn sie roh verzehrt werden und mit Humanpathogenen kontaminiert sind, Krankheiten beim Menschen verursachen. Kontaminationen von Frischeprodukten mit bakteriellen Humanpathogenen wie Salmonella enterica können entlang der gesamten Produktionskette auftreten, und eine mögliche Kontaminationsquelle ist der Boden. Die Rhizosphäre und Phyllosphäre von Pflanzen sowie der Boden sind sehr heterogene Habitate, deren Bedingungen sich schnell verändern können, und das Überleben von Humanpathogenen in dieser Umwelt wird von vielen biotischen und abiotischen Faktoren beeinflusst. Bislang ist vieles über die Ökologie von Salmonella in der Umwelt noch nicht bekannt und das Ziel dieser Arbeit war es, das Wissen darüber zu erweitern, welche Faktoren die Persistenz von Salmonella in der pflanzlichen Umwelt beeinflussen. In dieser Arbeit wurden in Mikrokosmos- und Gewächshausversuchen Faktoren untersucht, die das Überleben von Salmonella unter definierten Bedingungen beeinflussen können. Kopfsalat (Lactuca sativa cv. Tizian) wurde als Modellpflanze verwendet und Salmonella enterica serovar Typhimurium Stamm LT2 als Modellhumanpathogen. S. Typhimurium LT2 wurde in den Boden inokuliert und das Überleben mithilfe kultivierungsabhängiger und -unabhängiger Methoden verfolgt. Zu den in dieser Arbeit untersuchten Faktoren gehört der Einfluss der Präadaption, d.h. der Bedingungen, denen Bakterien vor dem Einbringen in die untersuchte Umwelt ausgesetzt sind, auf das Überleben von S. Typhimurium LT2 sowie auf S. Typhimurium Stamm 14028s und S. enterica Serovar Senftenberg. In Mikrokosmosexperimenten wurde gezeigt, dass die Anzahl kultivierbarer Zellen von S. Typhimurium LT2 nach Präadaption signifikant höher im Vergleich zur Kontrolle ohne Präadaption war. Dies zeigt, dass Präadaptation das Überleben dieses Salmonella-Stamms im Boden fördert. Die Ergebnisse liefern einen Hinweis darauf, dass das für die Anzucht der Zellen für Inokulationsexperimente verwendete Medium einen stammspezifischen Effekt auf das Überleben im Boden hat. Das bedeutet, dass die Bedingungen, denen Zellen vor der Inokulation ausgesetzt sind, einen großen Einfluss auf das Überleben von Salmonella haben können. Im Hinblick auf die Vergleichbarkeit der Ergebnisse verschiedener Studien ist dieses Ergebnis von Bedeutung. Des Weiteren wurde die Hypothese untersucht, dass das Überleben von S. Typhimurium LT2 im Boden und die Besiedlung von Kopfsalatpflanzen mit S. Typhimurium LT2 aus kontaminiertem Boden durch die Behandlung des Bodens mit Klärschlamm oder die Inokulation der pflanzenparasitären Nematoden Meloidogyne hapla oder Pratylenchus crenatus in den Boden gefördert wird. Entgegen der Erwartung, dass Klärschlamm durch zusätzliche Nährstoffe das Überleben von Salmonella fördert, wurde jedoch eine höhere Anzahl kultivierbarer S. Typhimurium LT2 im unbehandelten Boden gefunden als im Boden, der mit Klärschlamm behandelt wurde. Zwischen Proben von Boden, der mit Nematoden inokuliert wurde, und Kontrollboden wurde kein Unterschied in der Anzahl kultivierbarer S. Typhimurium LT2 gefunden. In keiner der Blattproben, die nach 21 oder nach 49 Tagen von Kopfsalatpflanzen aus Boden mit Klärschlamm, mit Nematoden oder aus den jeweiligen Kontrollböden genommen wurden, wurde Salmonella detektiert. Diese Ergebnisse deuten darauf hin, dass die Gegenwart von Klärschlamm oder Nematoden im Boden nicht die Besiedelung von Kopfsalatpflanzen mit S. Typhimurium LT2 fördert und dass auch hohe Konzentrationen von S. Typhimurium LT2 im Boden nicht unbedingt zur Kontamination der oberirdischen Teile der Pflanze durch Internalisierung über die Wurzeln führen. Da vermutet wurde, dass das geringere Überleben von Salmonella im Boden, der mit Klärschlamm behandelt wurde, auf die konkurrierenden Mikroorganismen zurückzuführen war, erfolgte eine kultivierungsunabhängige Analyse der Behandlung des Bodens mit Klärschlamm im Hinblick auf Veränderungen der bakteriellen Gemeinschaft im Boden sowie mobiler genetischer Elemente (MGE) und Antibiotikaresistenzgene (ARG) in einem Mikrokosmosexperiment über vier Monate. Ein Vergleich der Diversität und Häufigkeit von ARGs in Bodenproben mit Klärschlamm im Vergleich zum unbehandelten Boden zeigte eine erhöhte relative Abundanz von Plasmiden, Integrons, Transposons und Resistenzgenen, die teilweise auch nach vier Monaten detektierbar waren. Die bakteriellen Gemeinschaften im Boden zeigten nach Behandlung mit Klärschlamm verringerte Diversität im Vergleich zum Kontrollboden, und die Unterschiede wurden im Verlauf des Versuchs geringer. Resistenzplasmide aus Klärschlamm, die auf das Gammaproteobacterium Pseudomonas putida übertragbar sind, wurden mithilfe der exogenen Plasmidisolierung aus Klärschlamm extrahiert. Die isolierten Plasmide gehörten mehrheitlich zur Inkompatibilitätsgruppe IncP-1, die einen breiten Wirtsbereich hat. Zusammenfassend wurde in dieser Arbeit das Wissen über die Faktoren, die das Überleben von Salmonella in der pflanzlichen Umwelt und im Boden beeinflussen, erweitert und gezeigt, dass das Schicksal von Salmonella in der Umwelt sehr komplex ist und viele Faktoren das Überleben beeinflussen.
Auf Wunsch des Autors / der Autorin ist diese Dissertation nur als Druckausgabe verfügbar.Fresh fruits and vegetables are increasingly recognized as part of a healthy diet. However, disease outbreaks caused by Salmonella linked to fresh produce indicate that raw fruits and vegetables could be a vector for human pathogens. Contamination of fresh produce with Salmonella can occur along the whole production chain and one possible source is contaminated soil. Soil, rhizosphere and phyllosphere are heterogenous habitats where conditions can change quickly and survival of human pathogens in this environment is influenced by various biotic and abiotic factors. So far, the ecology of Salmonella in the environment is largely unknown and this thesis aimed at extending the knowledge of factors influencing the persistence of Salmonella in the soil-plant environment.In this thesis, microcosm and greenhouse experiments were conducted to analyze factors influencing the fate of Salmonella under defined conditions. Lettuce (Lactuca sativa cv. Tizian) was used as a model plant and Salmonella enterica serovar Typhimurium strain LT2 as a model human pathogen. S. Typhimurium LT2 was inoculated into soil and its fate was monitored using cultivation-dependent and -independent methods.Among the factors investigated in this thesis, the influence of preadaptation, meaning the conditions which the bacteria encounter before their introduction into the analyzed environment, on the survival of S. Typhimurium LT2 was investigated in soil microcosms. It was found that numbers of cultivable S. Typhimurium LT2 cells were significantly higher in the treatment with preadaptation than in the respective treatmment without preadaptation, showing that preadaptation can prolong survival of this strain in soil. These results indicate that the medium used to pre-grow Salmonella before inoculation into soil influenced the ability to survive in soil in a strain-specific manner. Therefore, conditions which bacteria encounter before their introduction into the environment might have a major influence on their survival and should be considered also with respect to comparability between studies.
Furthermore, in this thesis it was analyzed whether survival of S. Typhimurium LT2 inoculated into soil and colonization of lettuce plants by this strain is fostered by addition of sewage sludge or the plant-parasitic nematodes Meloidogyne hapla or Pratylenchus crenatus to soil. Unexpectedly, higher counts of cultivable S. Typhimurium LT2 were observed in untreated soil compared to soil with sludge. There were no differences in numbers of cultivable Salmonella in samples with nematode inoculation compared to control samples. No S. Typhimurium LT2 was detected in any of the leaf samples of lettuce plants grown in soil that was inoculated with S. Typhimurium LT2 after 21 and 49 days; neither in the samples where sludge or nematodes were added to the soil nor in the respective controls, indicating that the presence of sewage sludge or nematodes in soil did not foster colonization of lettuce plants by S. Typhimurium LT2. This suggests that the presence of Salmonella in soil even in relatively high concentrations and after addition of sewage sludge or plant-parasitic nematodes does not necessarily lead to a contamination of the aboveground part of plants by internalization through the roots.The application of sewage sludge to soil was also analyzed with respect to the dynamics of the bacterial soil community as well as its associated mobile genetic elements (MGEs) and antibiotic resistance genes (ARGs) in a microcosm experiment over the course of four months. Comparison of the microbial diversity and relative abundances of ARGs in soil samples with sewage sludge compared to control soil revealed increased relative abundance of plasmids, integrons, transposons and resistance genes that in some cases were still detectable after four months. Soil bacterial communities showed reduced richness and diversity compared to control soil but differences decreasing with time. Resistance plasmids were captured directly from sewage sludge in Pseudomonas putida. The majority of the plasmids isolated belonged to the broad host range IncP-1 plasmids.Altogether, this thesis extends the knowledge of factors influencing the fate of Salmonella in the soil - plant environment demonstrating that the fate of Salmonella in the environment of plants is very complex with many factors influencing its survival.
Upon author request this thesis is available as printed version only
Diversity of Baculoviruses isolated from cutworms (Agrotis spp.)
No full textBaculoviruses (Baculoviridae) are double-stranded DNA viruses which infect the larval stages of insects belonging to the orders Lepidoptera, Hymenoptera and Diptera. Due to their narrow host range and high virulence to target insects, different baculoviruses have been used as biological control agents in pest control. Severe soil pests of many agricultural and horticultural crops, which are difficult to be controlled, are larvae of the genus Agrotis (Lepidoptera: Noctuidae), also called cutworms. Their habitat is the soil or soil surface where they feed on seedlings, stems, and other parts of plants. So far, cutworms are mainly control by chemical pesticides, but biological control agents would be highly desirable for environmental reasons. Two of the most important cutworm pests are the common cutworm, Agrotis segetum (Denis & Schiffermüller), and the black cutworm, A. ipsilon (Hufnagel). At least four distinct baculovirus species, three of the genus Alphabaculovirus and one of the genus Betabaculovirus, were isolated from these two cutworm species. The alphabaculoviruses are the Agrotis segetum nucleopolyhedrovirus A (AgseNPV-A), Agrotis segetum nucleopolyhedrovirus B (AgseNPV-B), and Agrotis ipsilon nucleopolyhedrovirus (AgipNPV). The Agrotis segetum granulovirus (AgseGV) represents the betabaculovirus. Together with their two host species, from which they were first isolated and characterized, they form the so-called Agrotis baculovirus complex. Agrotis baculoviruses have the potential to be used as biological control agents for the control of Agrotis cutworms. However, in-depth knowledge and a full characterization of their biology, molecular setup, and virulence parameters are required for a successful registration and application in the field. In this study the genome sequence of AgseNPV-B was fully sequenced. Its genome is 148,981 bp in length and codes for 150 putative open reading frames. Whole genome comparisons with AgseNPV-A and AgipNPV, whose genome sequences have been published previously, suggested that AgseNPV-B belongs to a new species of the Agrotis baculovirus complex. Phylogenetic analysis indicated a very close relationship to AgipNPV and it could be concluded that both viruses are two distinct species at an early stage of separation. Whole genome alignments revealed a different number of viral enhancing factor (vef) gene copies in AgseNPV-A, AgseNPV-B and AgipNPV as one of the most striking distinguishing features between their genomes. VEFs are known to affect the virulence of baculoviruses. A putative site of genomic recombination was found in the region of the cathepsin and chitinase genes where the high co-linearity of the genomes of all three Agrotis nucleopolyhedroviruses was interrupted by inversions, deletions, or insertions. A putative fifth Agrotis baculovirus, the Agrotis exclamationis nucleopolyhedrovirus (AgexNPV), was suggested to be an isolate of AgseNPV-B due to high nucleotide sequence similarities of partial genomic regions. Based on the genome sequences of AgseNPV-A, AgseNPV-B, AgipNPV and AgseGV a multiplex PCR based method for the identification of these Agrotis baculoviruses was established. Highly specific oligonucleotide primers specific for the polyhedrin (polh) or granulin (gran) genes of the four viruses were developed and resulted in discriminating PCR fragments. Furthermore, this method allowed the quantitation of AgseGV and AgseNPV-B by quantitative PCR (qPCR). Since co-infections of AgseGV and AgseNPV-B have been observed and a combination of both viruses was considered as a combined biological control agent, the potential interaction of both viruses in mixed infections was investigated. Potential interactions between AgseNPV-B and AgseGV were examined in activity studies using single virus as well as combined virus infections of neonate A. segetum larvae. Mortality rates were determined and the virus progeny produced in individual larvae was quantified by using the newly established qPCR method of quantitation of AgseNPV-B and AgseGV. As a result, combinations of AgseNPV-B and AgseGV did not exhibit an advantageous effect in terms of pest control. Neither an increase in mortality rates in mixed virus treatments in comparison with single virus treatments, nor an increase in production of AgseNPV-B or AgseGV progeny in coinfected larvae was observed. On the contrary, a competitive behavior of both viruses in mixed infections could be concluded. The present thesis contribute to the biological control of Agrotis cutworms by providing extensive insight into the molecular setup of these viruses and the characterization of AgseNPV-B as a new Alphabaculovirus species. The use and registration of baculoviruses as biocontrol agents rely on such virus characterizations as well as on virus activity studies that were performed for AgseNPV-B and AgseGV. The new technique in Agrotis baculovirus detection and quantitation will facilitate future single and mixed infection studies of AgseNPV-B and AgseGV, as well as other combinations of Agrotis baculoviruses.
Auf Wunsch des Autors / der Autorin ist diese Dissertation nur als Druckausgabe verfügbar.Baculoviruses (Baculoviridae) are double-stranded DNA viruses which infect the larval stages of insects belonging to the orders Lepidoptera, Hymenoptera and Diptera. Due to their narrow host range and high virulence to target insects, different baculoviruses have been used as biological control agents in pest control. Severe soil pests of many agricultural and horticultural crops, which are difficult to be controlled, are larvae of the genus Agrotis (Lepidoptera: Noctuidae), also called cutworms. Their habitat is the soil or soil surface where they feed on seedlings, stems, and other parts of plants. So far, cutworms are mainly control by chemical pesticides, but biological control agents would be highly desirable for environmental reasons. Two of the most important cutworm pests are the common cutworm, Agrotis segetum (Denis & Schiffermüller), and the black cutworm, A. ipsilon (Hufnagel). At least four distinct baculovirus species, three of the genus Alphabaculovirus and one of the genus Betabaculovirus, were isolated from these two cutworm species. The alphabaculoviruses are the Agrotis segetum nucleopolyhedrovirus A (AgseNPV-A), Agrotis segetum nucleopolyhedrovirus B (AgseNPV-B), and Agrotis ipsilon nucleopolyhedrovirus (AgipNPV). The Agrotis segetum granulovirus (AgseGV) represents the betabaculovirus. Together with their two host species, from which they were first isolated and characterized, they form the so-called Agrotis baculovirus complex. Agrotis baculoviruses have the potential to be used as biological control agents for the control of Agrotis cutworms. However, in-depth knowledge and a full characterization of their biology, molecular setup, and virulence parameters are required for a successful registration and application in the field. In this study the genome sequence of AgseNPV-B was fully sequenced. Its genome is 148,981 bp in length and codes for 150 putative open reading frames. Whole genome comparisons with AgseNPV-A and AgipNPV, whose genome sequences have been published previously, suggested that AgseNPV-B belongs to a new species of the Agrotis baculovirus complex. Phylogenetic analysis indicated a very close relationship to AgipNPV and it could be concluded that both viruses are two distinct species at an early stage of separation. Whole genome alignments revealed a different number of viral enhancing factor (vef) gene copies in AgseNPV-A, AgseNPV-B and AgipNPV as one of the most striking distinguishing features between their genomes. VEFs are known to affect the virulence of baculoviruses. A putative site of genomic recombination was found in the region of the cathepsin and chitinase genes where the high co-linearity of the genomes of all three Agrotis nucleopolyhedroviruses was interrupted by inversions, deletions, or insertions. A putative fifth Agrotis baculovirus, the Agrotis exclamationis nucleopolyhedrovirus (AgexNPV), was suggested to be an isolate of AgseNPV-B due to high nucleotide sequence similarities of partial genomic regions. Based on the genome sequences of AgseNPV-A, AgseNPV-B, AgipNPV and AgseGV a multiplex PCR based method for the identification of these Agrotis baculoviruses was established. Highly specific oligonucleotide primers specific for the polyhedrin (polh) or granulin (gran) genes of the four viruses were developed and resulted in discriminating PCR fragments. Furthermore, this method allowed the quantitation of AgseGV and AgseNPV-B by quantitative PCR (qPCR). Since co-infections of AgseGV and AgseNPV-B have been observed and a combination of both viruses was considered as a combined biological control agent, the potential interaction of both viruses in mixed infections was investigated. Potential interactions between AgseNPV-B and AgseGV were examined in activity studies using single virus as well as combined virus infections of neonate A. segetum larvae. Mortality rates were determined and the virus progeny produced in individual larvae was quantified by using the newly established qPCR method of quantitation of AgseNPV-B and AgseGV. As a result, combinations of AgseNPV-B and AgseGV did not exhibit an advantageous effect in terms of pest control. Neither an increase in mortality rates in mixed virus treatments in comparison with single virus treatments, nor an increase in production of AgseNPV-B or AgseGV progeny in coinfected larvae was observed. On the contrary, a competitive behavior of both viruses in mixed infections could be concluded. The present thesis contribute to the biological control of Agrotis cutworms by providing extensive insight into the molecular setup of these viruses and the characterization of AgseNPV-B as a new Alphabaculovirus species. The use and registration of baculoviruses as biocontrol agents rely on such virus characterizations as well as on virus activity studies that were performed for AgseNPV-B and AgseGV. The new technique in Agrotis baculovirus detection and quantitation will facilitate future single and mixed infection studies of AgseNPV-B and AgseGV, as well as other combinations of Agrotis baculoviruses.
Upon author request this thesis is available as printed version only
Nutraceutical components, antioxidant activity and color of eleven varieties of prickly pear (Opuntia sp.)
No full textIn Mexico, there are 50 recorded varieties of the prickly pear fruit. National production covers only the white-pulp fruit, but other red varieties have export potential; however, their nutraceutical properties are unknown. The pulp and peel (underutilized tissue) of the pigmented fruits of the genus Opuntia sp. are marketed on a limited basis. They represent an alternative source of stable pigments (betalains), which are associated with antioxidant properties, for the agroindustry. The objective was to assess the content of nutraceutical components, antioxidant activity, and peel and pulp color of 11 varieties of the prickly pear fruit that are marketed on a small scale. Statistical analysis revealed that Roja Villanueva peel had the highest betalain content (39.97 mg 100 g-1 FW). Alteña Blanca peel demonstrated the highest concentration of phenolic compounds (618.39 mg GAE 100 g-1 FW), whereas Alteña Roja had the highest ascorbic acid content (37.14 mg AAE 100 g-1 FW). The greatest nutraceutical potential was observed in the pulp of the non-marketed Tzaponopal Rojo variety of the species O. robusta var. larreyi, due to the high antioxidant activity (0.0183 mg mL-1), as well as the darkest color (‹ hue value, 12.31) and the lowest lightness (‹ luminosity, 19.31), which coincides with the highest betalain concentration
Characteristic amino acids in tea leaves as quality indicator for evaluation of Wuyi Rock Tea in different cultured regions: Characteristic amino acids in Wuyi Rock Tea
No full textFree amino acid compositions in Wuyi Rock Tea leaves from Yu (authentic rock region), Guiyan (semi-authentic rock region) and Qishan (ordinary region) tea plantations were analyzed. Results showed that contents of 18 free amino acids were 1.6-2.0 times higher in Yu and Guiyan than that in Qishan. The theanine contents reached to 17-20 mg g-1 in Yu and Guiyan, while it was less than 10 mg g-1 in Qishan. Hierarchical cluster analysis and principal component analysis were effective in distinguishing Rock Tea from different regions. The ratios of theanine, sweet and umami amino acids were 8%, 5% and 6% higher, respectively in Yu than that in Qishan. Sensory evaluation score were positively correlated with the ratios of theanine, sweet and umami amino acids (P < 0.05 or P < 0.01). Our results highlight that the favourite characteristic amino acids are dominant contributors to sweet aftertaste of Rock Tea