Thinopyrum-Arten als Donoren von Resistenzen gegen wichtige Pathogene im Winterweizen (Triticum aestivum L.)

Zusammenfassung In bekannten Kulturformen des Weizens (Triticum aestivum L.) werden immer seltener neue Resistenzen gegen wirtschaftlich bedeutende Krankheiterreger (Oculimacula spp, Fusarium culmorum, Puccina triticina und Barley yellow dwarf Virus) identifiziert. Die Identifikation von Resistenzgenen aus der Wildtypform Thinopyrum spp. und deren anschließende Nutzung in der Weizenzüchtung ist somit Ziel dieses Projekts. Für ein markergestütztes Rückkreuzungsprogramm stehen zwei Translokationslinien, PI583794 und PI611939, als Träger einer Thinopyrum- Introgession auf Chromosom 4D, sowie 3 Weizensorten (Boomer, Esket und Mirage) zur Verfügung. Für die phänotypische Charakterisierung wurden diese Linien auf ihre Resistenz gegen die genannten Erreger getestet. Parallel dazu erfolgte die genotypische Charakterisierung. Mit den spezifischen Primern STSJ15 und 2P1/2P2 konnte die Introgression nachgewiesen werden. Zur Bestimmung der Größe des Introgressionsfragments wurden ausgewählte Genotypen der BC1F1 und BC2F1mit polymorphen SSRs analysiert, um auf diese Weise Genotypen zu identifizieren, welche ein möglichst kleines Introgessionsfragment aufweisen, jedoch resistent sind. Stichwörter: Weizen (Triticum aestivum L.), Thinopyrum intermedium, Thinopyrum ponticum, Oculimacula spp, Fusarium culmorum, Puccina triticina, Barley yellow dwarf Virus, PI583794, PI611939, STSJ15, 2P1/2P2   Abstract In order to broaden the genetic base in Triticum aestivum against economically important pathogens (Oculimacula spp, Fusarium culmorum, Puccina triticina and Barley yellow dwarf virus) wheat translocation lines carrying a chromosomal segment derived from Thinopyrum spp are tested for resistance and analyzed by molecular techniques. Two introgression lines PI583794 and PI611939 as carriers of the Thinopyrum-fragment, as well as 3 wheat cultivars (Boomer, Esket and Mirage) are used for a marker-assisted back crossing program. For the phenotypic characterization, these lines were tested for resistance against these above mentioned pathogens. In addition to the genotypic characterization was carried out using Thinopyrum specific primers STSJ15 and 2P1/2P2 to identify the introgression.. To define the size of the introgressions-fragments selected genotypes of the BC1F1 and BC2F1 were tested with polymorphic microsatellites (SSRs) in order to identify those genotyes carrying only a small fragment of Thinopyrum spp. but still being resistant. Keywords: wheat (Triticum aestivum L.), Thinopyrum intermedium, Thinopyrum ponticum, Oculimacula spp, Fusarium culmorum, Puccina triticina, Barley yellow dwarf, PI583794; PI611939, STSJ15, 2P1/2P

Metabolic and Transcriptomic Phenotyping of Inorganic Carbon Acclimation in the Cyanobacterium Synechococcus elongatus PCC 79421[W]

The amount of inorganic carbon is one of the main limiting environmental factors for photosynthetic organisms such as cyanobacteria. Using Synechococcus elongatus PCC 7942, we characterized metabolic and transcriptomic changes in cells that had been shifted from high to low CO2 levels. Metabolic phenotyping indicated an activation of glycolysis, the oxidative pentose phosphate cycle, and glycolate metabolism at lowered CO2 levels. The metabolic changes coincided with a general reprogramming of gene expression, which included not only increased transcription of inorganic carbon transporter genes but also genes for enzymes involved in glycolytic and photorespiratory metabolism. In contrast, the mRNA content for genes from nitrogen assimilatory pathways decreased. These observations indicated that cyanobacteria control the homeostasis of the carbon-nitrogen ratio. Therefore, results obtained from the wild type were compared with the MP2 mutant of Synechococcus 7942, which is defective for the carbon-nitrogen ratio-regulating PII protein. Metabolites and genes linked to nitrogen assimilation were differentially regulated, whereas the changes in metabolite concentrations and gene expression for processes related to central carbon metabolism were mostly similar in mutant and wild-type cells after shifts to low-CO2 conditions. The PII signaling appears to down-regulate the nitrogen metabolism at lowered CO2, whereas the specific shortage of inorganic carbon is recognized by different mechanisms