Approaches in Enhancing Antioxidant Defense in Plants

This Special Issue, “Approaches in Enhancing Antioxidant Defense in Plants” published 13 original research works and a couple of review articles that discuss the various aspects of plant oxidative stress biology and ROS metabolism, as well as the physiological mechanisms and approaches to enhancing antioxidant defense and mitigating oxidative stress. These papers will serve as a foundation for plant oxidative stress tolerance and, in the long term, provide further research directions in the development of crop plants’ tolerance to abiotic stress in the era of climate change

Gezielte Mutagenese mit Cas-Endonukleasen zur Etablierung von Bymovirus-Resistenzen in Gerste

Seit der neolithischen Revolution haben Domestikation und Pflanzenzüchtung die vom Menschen angebauten Pflanzen grundlegend verändert - aus Wildpflanzen wurden Kulturpflanzen. Insbesondere ab dem 19. Jahrhundert intensivierten die ersten Pflanzenzüchterinnen und -züchter ihre Arbeit zur Verbesserung von Kulturpflanzen. Mit der aufkommenden wissenschaftlichen Disziplin der Genetik wuchs das Verständnis dafür, wie Eigenschaften vererbt und verändert werden. Die moderne Genomik mit der Sequenzierung von Pangenomen und leistungsfähiger Bioinformatik trägt wesentlich dazu bei, die genetischen Grundlagen dieser Eigenschaften und die Bedeutung genetischer Veränderungen immer besser zu verstehen. Mit der Genomeditierung steht heute ein Methodenset zur Verfügung, um Gene von Kulturpflanzen gezielt zu verändern, sowohl für die wissenschaftliche Untersuchung von Genfunktionen als auch für die züchterische Verbesserung von Pflanzen. Insbesondere die vom mikrobiellen Immunsystem CRISPR-Cas abgeleiteten Cas-Endonukleasen haben sich dabei als nützliches und praktikables Werkzeug erwiesen. In der vorliegenden Arbeit wurde die CRISPR-assoziierte Endonuklease Cas9 zur gezielten Mutagenese zweier bekannter Anfälligkeitsgene der Gerste gegen die Gelbmosaikvirose eingesetzt. Die Gelbmosaikvirose ist eine der bedeutendsten Krankheiten der Gerste (Hordeum vulgare L.) in Europa und Asien. Sie wird von den beiden Bymoviren Gerstengelbmosaikvirus (Barley Yellow Mosaic Virus, BaYMV) und Mildes Gerstenmosaikvirus (Barley Mild Mosaic Virus, BaMMV) verursacht. Mit Eukaryotic Translation Initiation Factor 4E (EIF4E) und Protein Disulfide Isomerase-Like 5-1 (PDIL5-1) sind zwei Anfälligkeitsgene der Gerste bekannt, für die resistenzvermittelnde Allele beschrieben wurden. Derzeit sind fast alle Wintergerstensorten in Europa resistent gegen BaYMV und BaMMV, jedoch basieren diese Resistenzen fast ausschließlich auf den EIF4E-Allelen rym4 und rym5. Doch diese Resistenzen wurden bereits von angepassten Virusstämmen gebrochen, sodass ein Bedarf an neuen Resistenzvarianten und -mechanismen besteht. Ziel dieser Arbeit war es daher, neue resistenzvermittelnde Allele von EIF4E zu generieren sowie die in Gerstenlandrassen beschriebenen, resistenzvermittelnden Allele von PDIL5-1 in anfälligen Genotypen zur reproduzieren. Dafür wurden beide Gene mittels Cas9 gezielt mutiert, wobei erfolgreich verschiedene Knockout- und Basenmutationen in PDIL5-1 sowie Knockout-Mutationen in EIF4E induziert werden konnten. Die Nachkommenschaften der Primärmutanten wurden manuell mit BaMMV infiziert und sowohl die Knockout-Mutationen in EIF4E und PDIL5-1 als auch die Basensubstitutionen in PDIL5-1 führten zur Resistenz gegen das Virus. Im Gegensatz zu PDIL5-1 ging der Knockout von EIF4E jedoch mit einer Reduktion des Kornertrags einher. Aus diesem Grund wurde für dieses Kandidatengen zusätzlich die Baseneditierung in Wintergerste etabliert. Mihilfe von Cas9-Derivaten, die gezielt C-zu-T- und A-zu-G-Basen-substitutionen induzieren, wurden so insgesamt zehn neue Allele von EIF4E erzeugt, die in nachfolgenden Arbeiten auf ihre resistenzvermittelnden Eigenschaften überprüft werden können. Die vorliegende Arbeit liefert konkrete Beispiele dafür, wie mithilfe der Genomeditierung Pflanzenforschung und -züchtung, insbesondere im Hinblick auf Krankheitsresistenzen, verbessert werden können. Mit den Methoden der gezielten Mutagenese ist es möglich, Genvarianten für vorteilhafte Eigenschaften, die in der Kulturpflanzenvielfalt (z.B. in Genbanken) mithilfe der Hochdurchsatzsequenzierung und modernen Methoden der Genetik immer schneller gefunden werden, für die Pflanzenzüchtung nutzbar zu machen. Damit kann ein wesentlicher Beitrag für eine nachhaltigere Landwirtschaft geleistet werden.Since the Neolithic Revolution, domestication and plant breeding have extensively changed the shape of the plants cultivated by humans - wild plants became crop plants. Especially from the 19th century onwards, the first plant breeders intensified their work on crop plant improvement and with genetics as an emerging scientific discipline, they increasingly understood how traits are inherited and modified. Modern genomics, with sequencing of pangenomes and powerful bioinformatics, is playing a major role in helping understand the genetic basis of these traits and the significance of genetic changes. With gene editing, a whole suite of methods is now available to specifically modify genes of crop plants. In particular, CRISPR-associated (Cas) endonucleases derived from the microbial CRISPR-Cas immune system have been proven to be a useful and practical tool. In the present work, the Cas9 endonuclease was used for targeted mutagenesis of two previously known susceptibility genes of barley against the barley yellow mosaic disease. Caused by the Barley yellow mosaic virus (BaYMV) and the Barley mild mosaic virus (BaMMV), the barley yellow mosaic disease is one of the most important viral diseases of barley (Hordeum vulgare L.) in Europe and Asia. With the Eukaryotic Translation Initiation Factor 4E (EIF4E) and the Protein Disulfide Isomerase-Like 5-1 (PDIL5-1), two susceptibility genes of barley are known for which resistance-conferring alleles have already been described. Currently, almost all winter barley varieties in Europe are resistant to BaYMV and BaMMV, but this resistance is based almost exclusively on the EIF4E alleles rym4 and rym5. However, this resistance has already been overcome by some adapted virus strains, which is why there is an urgent need for new resistance variants and mechanisms. Therefore, the aim of this work was to generate new resistance-mediating alleles of EIF4E and to reproduce in susceptible genotypes the resistance-mediating alleles of PDIL5-1 that have been described in barley landraces. For this purpose, both genes were specifically mutated using Cas9, successfully inducing different knockout and base mutations in PDIL5-1 as well as knockout mutations in EIF4E. The progeny of the primary mutants was mechanically infected with BaMMV and both the Knockout mutations in EIF4E and PDIL5-1 and the base substitutions in PDIL5-1 resulted in resistance to the virus. However, unlike PDIL5-1, knockout of EIF4E was accompanied by a reduction in grain yield. For this reason, base editing was established in winter barley for this candidate gene. Using Cas9 derivatives that specifically induce C-to-T and A-to-G base substitutions, a total of ten new alleles of EIF4E were generated which can be tested for their resistance-mediating properties in subsequent work. The present work provides concrete examples of how gene editing can be used to improve plant research and plant breeding, especially with regard to disease resistance. With the methods of targeted mutagenesis, it is possible to deploy beneficial gene variants which are being found ever faster by taking advantage of the crop diversity (e.g. in gene banks) and with the help of high-throughput sequencing and modern methods of genetics. This is expected to make a significant contribution to more sustainable agriculture

Ectomycorrhiza Development : Investigation of Selected Ectomycorrhiza Induced Poplar Genes

Mutualistic interaction such as ectomycorrhiza (ECM) is important for forest ecosystem function. Here two kingdoms, plant and fungi, form a symbiosis and exchanges nutrients and carbohydrates. A bottle neck in ectomycorrhizal research is the time demand for transgenic plant generation. Formation of so-called composite plants, where transgenic roots are formed on non-transgenic shoots, is an alternative strategy. An Agrobacterium rhizogenes-mediated root transformation protocol was developed in this work using axenic Populus tremula A tremuloides and P. tremula A alba cuttings. Out of four different A. rhizogenes strains, K599 was found to be the most suitable one. Roots of composite poplars were able to form ectomycorrhiza when inoculated with Amanita muscaria. By using real time quantitative PCR a comparative analysis of transcript levels was done for selected genes in mycorrhized and non-mycorrhized poplar fine roots. A total of 50 ectomycorrhiza-induced genes were chosen based on a genome wide microarray analysis (Nehls, unpublished). As the array oligomers were designed based on Populus trichocarpa genome but the array hybridization was performed using P. tremula x tremuloides cDNA, cross hybridization leading to misinterpretation is feasible. Therefore, the first step was to screen P. tremula/P. tremuloides datasets for the best matching homologs. After primer design and first qRT-PCR tests 14 candidate genes remained. Finally, expression analysis with several independent batches of poplar fine roots and mycorrhizas were obtained for six genes. Two genes, a transcription factor (TF- Potri.008G071100) belonging to the AP2/ERF superfamily and a potential glycosyltransferase (GT- Potri.007G095000) revealing the highest gene expression difference, were selected for further analysis. Fusion with super yellow fluorescent protein revealed a probable subcellular localization of Potri.007G095000 in nucleus and cytoplasm and Potri.008G071100 in nucleus. Following their establishment, composite poplars were used for promoter analysis of the selected genes. For this purpose, around 3 kb promoter fragments were amplified from genomic DNA of P. tremula x tremuloides, successively shortened from the 5' end and the resulting fragments were cloned in front of the coding sequence of a peroxisomal located yellow fluorescent protein. The longest promoter-reporter constructs were used for generation of composite poplars. No reliable ECM induced expression was found for the TF and the GT indicating the need for longer promoter fragments. Furthermore, as the best Arabidopsis TF homolog is known to be auto-regulated, the identification of potential cis-elements in the promoter region was planned. Therefore, protein overexpression in E. coli was initiated. However, all attempts of receiving a natively folded protein in soluble form were unsuccessful

Organelle Genetics in Plants

Chloroplasts in photosynthetic organisms and mitochondria in a vast majority of eukaryotes, contain part of the genetic material of a eukaryotic cell. The organisation and inheritance patterns of this organellar DNA are quite different to that of nuclear DNA. Present-day chloroplast and mitochondrial genomes contain only a few dozen genes. Nevertheless, these organelles harbor several thousand proteins, the vast majority of them encoded by the nucleus. As a result, the expression of nuclear and organelle genomes has to be very precisely coordinated. The selection of experimental and review papers of this book covers a wide range of topics related to chloroplasts and plant mitochondria research, illustrating recent advances and diverse insights into the field of organelle genetics in plants. These works represent some of the latest research on the genetics, genomics, and biotechnology of plant mitochondria and chloroplasts, and they are of significant broad interest for the community of plant scientists, especially for those working in the subjects related to organelle genetic

ACARORUM CATALOGUS IX. Acariformes, Acaridida, Schizoglyphoidea (Schizoglyphidae), Histiostomatoidea (Histiostomatidae, Guanolichidae), Canestrinioidea (Canestriniidae, Chetochelacaridae, Lophonotacaridae, Heterocoptidae), Hemisarcoptoidea (Chaetodactylidae, Hyadesiidae, Algophagidae, Hemisarcoptidae, Carpoglyphidae, Winterschmidtiidae)

The 9th volume of the series Acarorum Catalogus contains lists of mites of 13 families, 225 genera and 1268 species of the superfamilies Schizoglyphoidea, Histiostomatoidea, Canestrinioidea and Hemisarcoptoidea. Most of these mites live on insects or other animals (as parasites, phoretic or commensals), some inhabit rotten plant material, dung or fungi. Mites of the families Chetochelacaridae and Lophonotacaridae are specialised to live with Myriapods (Diplopoda). The peculiar aquatic or intertidal mites of the families Hyadesidae and Algophagidae are also included.Publishe

InterDrought-V

Drought is weather-related natural disaster, which affects vast regions for months or years and has impact on food production. Drought is related to a deficiency of precipitation over a season or an extended period of time. The most immediate consequence is a fall in crop production, due to inadequate and poorly distributed rainfall. Given the severity of drought, a central challenge for researchers and policy makers is to device technologies that lend greater resilience to agricultural production under this stress. InterDrought conferences, in view of above, serve as a platform for presenting and debating key issues and strategies relevant for improving drought and other stress tolerance in crops. The main mission of the conference is to explore the possibilities of scientific and technological applications in crop improvement. In continuation of earlier InterDrought Conferences held in France (ID-I, 1995), Italy (ID-II, 2005), China (ID-III, 2009) and Australia (ID-IV, 2013), the next InterDrought Conference, InterDrought-V, is being organized in India..