Sterols as dietary markers for Drosophila melanogaster.

During cold acclimation fruit flies switch their feeding from yeast to plant food, however there are no robust molecular markers to monitor this in the wild. Drosophila melanogaster is a sterol auxotroph and relies on dietary sterols to produce lipid membranes, lipoproteins and molting hormones. We employed shotgun lipidomics to quantify eight major food sterols in total lipid extracts of heads and genital tracts of adult male and female flies. We found that their sterol composition is dynamic and reflective of fly diet in an organ-specific manner. Season-dependent changes observed in the organs of wild-living flies suggested that the molar ratio between yeast (ergosterol, zymosterol) and plant (sitosterol, stigmasterol) sterols is a quantifiable, generic and unequivocal marker of their feeding behavior suitable for ecological and environmental population-based studies. The enrichment of phytosterols over yeast sterols in wild-living flies at low temperatures is consistent with switching from yeast to plant diet and corroborates the concomitantly increased unsaturation of their membrane lipids

Vergleichende genetische Kartierung der Feuerbrandresistenz bei Malus sp. = Comparative genetic mapping of resistance to fire blight in Malus sp.

Für die vergleichende Kartierung von Feuerbrandresistenz bei Malus wurden vier Populationen bearbeitet, die als einen Elter einen Donor für Feuerbrandresistenz und als zweiten Elter die anfällige Sorte ‘Idared’ hatten. Als Donoren für Widerstandsfähigkeit wurden definierte Abstammungen der Wildarten M. baccata, M. fusca, M. ×robusta und die widerstandsfähige Pillnitzer Apfelsorte ‘Rewena’ genutzt. Die Phänotypisierung der Populationen erfolgte in unterschiedlichen Jahren durch Inokulation von vegetativen Trieben mit dem Erwinia amylovora-Isolat Ea222 und anderen definierten Isolaten unter Gewächshausbedingungen. Der Befall der Triebe wurde als Befallsrate, dem Verhältnis der befallenen Trieblänge zur Gesamttrieblänge, ermittelt. Je nach Isolat und Population variierte die durchschnittliche Befallsrate zwischen 10 bis 82%. Die Genotypisierung der Nachkommen zur Erstellung genetischer Karten erfolgte mit Mikrosatelliten-, SNP- und DArT-Markern. Die genetischen Kopplungskarten wurden mittels Joinmap 4.0 und die Resistenz gegenüber Feuerbrand mit MapQTL5.0 kartiert. Major-QTLs konnten für M. ×robusta auf Kopplungsgruppe 3, für M. baccata auf Kopplungsgruppe 12 und für M. fusca auf Kopplungsgruppe 10 detektiert werden. Während die Feuerbrand-QTLs von M. ×robusta 5 und M. fusca je nach Jahr bis zu ca. 87% der phänotypischen Varianz erklären können, erklärt der QTL von M. baccata nur ca. 45%, was die Existenz eines zweiten QTL nahe legt. Für die resistente Sorte ‘Rewena’ konnte kein QTL detektiert werden. Mit den Markern, die im Bereich der detektierten QTLs liegen, kann auf Resistenz gegenüber Feuerbrand selektiert werden. Damit ist eine Kombinierung unterschiedlicher Feuerbrandresistenz-QTLs möglich. Auf dieser Basis können zukünftig Sorten gezüchtet werden, die dauerhaft widerstandsfähig gegenüber Feuerbrand sind, um diese dann dem deutschen Obstbau zur Verfügung stellen zu könne

QTL mapping for resistance to fire blight using several Erwinia amylovora strains resulting in different host-pathogen interactions

QTL mapping of fire blight resistance in apple is an effective tool to determine associations between regions in the genome of apple and resistance to the bacterial disease. Several wild Malus accessions of different apple species have been identified as resistant to fire blight making them valuable as donors for the introgression of resistance to the cultivated apple Malus × domestica Borkh. Resistant accessions of the wild species M. baccata, M. fusca and M. × robusta 5 (Mr5) were inoculated with the wild type strain Ea1189 and the AvrRpt2EA deletion mutant (pZYRKD3-1). While M. baccata and M. fusca showed no symptoms to pZYRKD3-1, the resistance of M. × robusta 5 was overcome by pZYRKD3-1 with an average necrosis length of 52% respectively. Inoculation of the mapping population ‘Idared’ × Mr5 with the strain Ea 1189 results in the confirmation of the QTL on LG 3 in Mr5; this QTL completely broke down after inoculation with pZYRKD3-1, but two minor QTLs on LG 7 and LG 11 were detected

Essential role for the transcription factor Bhlhe41 in regulating the development, self-renewal and BCR repertoire of B-1a cells

Innate-like B-1a cells provide a first line of defense against pathogens, yet little is known about their transcriptional control. Here we identified an essential role for the transcription factor Bhlhe41, with a lesser contribution by Bhlhe40, in controlling B-1a cell differentiation. Bhlhe41-/-Bhlhe40-/- B-1a cells were present at much lower abundance than were their wild-type counterparts. Mutant B-1a cells exhibited an abnormal cell-surface phenotype and altered B cell receptor (BCR) repertoire exemplified by loss of the phosphatidylcholine-specific VH12Vκ4 BCR. Expression of a pre-rearranged VH12Vκ4 BCR failed to 'rescue' the mutant phenotype and revealed enhanced proliferation accompanied by increased cell death. Bhlhe41 directly repressed the expression of cell-cycle regulators and inhibitors of BCR signaling while enabling pro-survival cytokine signaling. Thus, Bhlhe41 controls the development, BCR repertoire and self-renewal of B-1a cells

Host resistance to Erwinia amylovora: germplasm, breeding, genetics

The most important bacterial disease affecting pome fruit is fire blight caused by Erwinia amylovora. It can cause devastating economic losses and is reliably controlled only by the application of antibiotics, which are banned in many European countries due to environmental, sustainable and consumer friendly issues. One solution could be the utilization of fire blight resistant cultivars in apple production. In 2003, we started an approach at Dresden-Pillnitz to detect different mechanisms conferring resistance to fire blight aimed at their combination in new cultivars. Four segregating populations were established to map QTLs for fire blight resistance. The donors used were three wild species accessions Malus baccata (MALD0004), M. fusca (MALD0045), M. × robusta 5 and the Pillnitz cultivar Rewena. The susceptible parent in each case was Idared. Grafted scions of each progeny were inoculated with E. amylovora strain Ea 222_JKI in at least for two years. Average percent lesion length (PLL) of all progenies was determined. Genetic linkage maps were established using DArT-, SCAR-, SNP-, and SSR-markers. Whereas in Rewena no QTL could be determined, major QTLs were detected in M. baccata on linkage group 12, in M. fusca on linkage group 10, and in M. × robusta 5 on linkage group 3 explaining up to around 50, 85 and 85% of the phenotypic variance, respectively. The case that all resistance QTLs are located on different linkage groups enhances the chance that different mechanisms are acting in the donors. Additionally, trees of the Idared by M. × robusta 5 population were planted in an orchard and flowers were inoculated in two consecutive years. The QTL on linkage group 3 could be confirmed after mappin

New and Interesting Fungi. 3

Seven new genera, 26 new species, 10 new combinations, two epitypes, one new name, and 20 interesting new host and / or geographical records are introduced in this study. New genera are: Italiofungus (based on Italiofungus phillyreae) on leaves of Phillyrea latifolia (Italy); Neolamproconium (based on Neolamproconium silvestre) on branch of Tilia sp. (Ukraine); Neosorocybe (based on Neosorocybe pini) on trunk of Pinus sylvestris (Ukraine); Nothoseptoria (based on Nothoseptoria caraganae) on leaves of Caragana arborescens (Russia); Pruniphilomyces (based on Pruniphilomyces circumscissus) on Prunus cerasus (Russia); Vesiculozygosporium (based on Vesiculozygosporium echinosporum) on leaves of Muntingia calabura (Malaysia); Longiseptatispora (based on Longiseptatispora curvata) on leaves of Lonicera tatarica (Russia). New species are: Barrmaelia serenoae on leaf of Serenoa repens (USA); Chaetopsina gautengina on leaves of unidentified grass (South Africa); Chloridium pini on fallen trunk of Pinus sylvestris (Ukraine); Cadophora fallopiae on stems of Reynoutria sachalinensis (Poland); Coleophoma eucalyptigena on leaf litter of Eucalyptus sp. (Spain); Cylindrium corymbiae on leaves of Corymbia maculata (Australia); Diaporthe tarchonanthi on leaves of Tarchonanthus littoralis (South Africa); Elsinoe eucalyptorum on leaves of Eucalyptus propinqua (Australia); Exophiala quercina on dead wood of Quercus sp., (Germany); Fusarium californicum on cambium of budwood of Prunus dulcis (USA); Hypomyces gamsii on wood of Alnus glutinosa (Ukraine); Kalmusia araucariae on leaves of Araucaria bidwillii (USA); Lectera sambuci on leaves of Sambucus nigra (Russia); Melanomma populicola on fallen twig of Populus canadensis (Netherlands), Neocladosporium syringae on branches of Syringa vulgarishorus (Ukraine); Paraconiothyrium iridis on leaves of Iris pseudacorus (Ukraine); Pararoussoella quercina on branch of Quercus robur (Ukraine); Phialemonium pulveris from bore dust of deathwatch beetle (France); Polyscytalum pinicola on needles of Pinus tecunumanii (Malaysia); Acervuloseptoria fraxini on Fraxinus pennsylvanica (Russia); Roussoella arundinacea on culms of Arundo donax (Spain); Sphaerulina neoaceris on leaves of Acer negundo (Russia); Sphaerulina salicicola on leaves of Salix fragilis (Russia); Trichomerium syzygii on leaves of Syzygium cordatum (South Africa); Uzbekistanica vitis-viniferae on dead stem of Vitis vinifera (Ukraine); Vermiculariopsiella eucalyptigena on leaves of Eucalyptus sp. (Australia)

Proof of existence of different host-pathogen interactions between the wild apple (Malus × robusta) and the causal agent of fire blight (Erwinia amylovora) by means of QTL mapping

Feuerbrand zählt zu den gefährlichsten Pflanzenkrankheiten im Kernobstanbau weltweit. Die Krankheit wird verursacht durch das Bakterium Erwinia amylovora (Burrill) Winslow. Eine effektive Bekämpfung des Feuerbrandes ist zurzeit nur mit streptomycinhaltigen Pflanzenschutzmitteln möglich. Deren Anwendung ist in Deutschland jedoch nur in Ausnahmefällen möglich. Ein Ausweg aus dieser Situation wird unter anderem auch im Anbau resistenter Sorten gesehen. Viele der im Anbau erfolgreichen Apfelsorten sind jedoch anfällig gegenüber Feuerbrand. Aus diesem Grund stellt die Züchtung feuerbrandresistenter Apfelsorten eines der Hauptziele in vielen Züchtungsprogrammen in der Welt dar. Resistenzen sind hauptsächlich bei Apfelwildarten beschrieben. Diese dienen somit als wichtige genetische Ressource für die Resistenzzüchtung. Bei einer ersten QTL-Kartierung in der Kreuzungspopulation 'Idared' x Malus × robusta 5 (Mr5) mit dem Erwinia amylovora Erregerstamm Ea222 konnte ein QTL auf Chromosom 3 in Mr5 detektiert werden. Das führt zu der Annahme, dass die Resistenz gegen Feuerbrand in Mr5 von einem einzelnen Gen determiniert wird. Auch nach Inokulation mit dem Wildtypstamm Ea1189 konnte der QTL auf Chromosom 3 nachgewiesen werden. Im Gegensatz dazu brach der QTL in Mr5 nach der Inokulation mit der avrRpt2 Deletionsmutante pZYRKD3-1 des Stammes Ea1189 zusammen. Die durchschnittliche Länge der Triebnekrose aller Nachkommen betrug 77% und 40% für die beiden Stämme pZYRKD3-1 und Ea1189. Die Ergebnisse deuten auf eine Gen-für-Gen Beziehung zwischen einem Resistenzgen des Wirtes und dem bakteriellen Effektorgen avrRpt2 von E. amylovora hin. Bei der Evaluierung der Apfelwildartenhybride Malus × robusta 5 sowie weiterer resistenter und anfälliger Apfelgenotypen mit unterschiedlichen Erwina-Stämmen konnten neben der Deletionsmutante zwei weitere Stämme gefunden werden, welche die Resistenz von Mr5 brechen. Die Stämme Ea 110 und Ea 3050 verursachten eine durchschnittliche Triebnekrose von 28% und 30%. Die durchschnittliche Triebnekrose betrug bei den anfälligen Apfelsorten zwischen 40% und 87%. Die resistenten Apfelwildarten Malus fusca, Malus floribunda und Malus baccata zeigten keine Symptome gegenüber allen getesteten Stämmen des Erregers. Diese Ergebnisse weisen auf unterschiedliche Resistenzmechanismen in der Wirt-Pathogen-Beziehung Malus – E. amylovora hin

Mapping of fire blight resistance in Malus ×robusta 5 flowers following artificial inoculation

Background Although the most common path of infection for fire blight, a severe bacterial disease on apple, is via host plant flowers, quantitative trait loci (QTLs) for fire blight resistance to date have exclusively been mapped following shoot inoculation. It is not known whether the same mechanism underlies flower and shoot resistance. Results We report the detection of a fire blight resistance QTL following independent artificial inoculation of flowers and shoots on two F1 segregating populations derived from crossing resistant Malus ×robusta 5 (Mr5) with susceptible ‘Idared’ and ‘Royal Gala’ in experimental orchards in Germany and New Zealand, respectively. QTL mapping of phenotypic datasets from artificial flower inoculation of the ‘Idared’ × Mr5 population with Erwinia amylovora over several years, and of the ‘Royal Gala’ × Mr5 population in a single year, revealed a single major QTL controlling floral fire blight resistance on linkage group 3 (LG3) of Mr5. This QTL corresponds to the QTL on LG3 reported previously for the ‘Idared’ × Mr5 and an ‘M9’ × Mr5 population following shoot inoculation in the glasshouse. Interval mapping of phenotypic data from shoot inoculations of subsets from both flower resistance populations re-confirmed that the resistance QTL is in the same position on LG3 of Mr5 as that for flower inoculation. These results provide strong evidence that fire blight resistance in Mr5 is controlled by a major QTL on LG3, independently of the mode of infection, rootstock and environment. Conclusions This study demonstrates for the first time that resistance to fire blight caused by Erwinia amylovora is independent of the mode of inoculation at least in Malus ×robusta 5

New and Interesting Fungi. 3

Seven new genera, 26 new species, 10 new combinations, two epitypes, one new name, and 20 interesting new host and / or geographical records are introduced in this study. New genera are: Italiofungus (based on Italiofungus phillyreae) on leaves of Phillyrea latifolia (Italy); Neolamproconium (based on Neolamproconium silvestre) on branch of Tilia sp. (Ukraine); Neosorocybe (based on Neosorocybe pini) on trunk of Pinus sylvestris (Ukraine); Nothoseptoria (based on Nothoseptoria caraganae) on leaves of Caragana arborescens (Russia); Pruniphilomyces (based on Pruniphilomyces circumscissus) on Prunus cerasus (Russia); Vesiculozygosporium (based on Vesiculozygosporium echinosporum) on leaves of Muntingia calabura (Malaysia); Longiseptatispora (based on Longiseptatispora curvata) on leaves of Lonicera tatarica (Russia). New species are: Barrmaelia serenoae on leaf of Serenoa repens (USA); Chaetopsina gautengina on leaves of unidentified grass (South Africa); Chloridium pini on fallen trunk of Pinus sylvestris (Ukraine); Cadophora fallopiae on stems of Reynoutria sachalinensis (Poland); Coleophoma eucalyptigena on leaf litter of Eucalyptus sp. (Spain); Cylindrium corymbiae on leaves of Corymbia maculata (Australia); Diaporthe tarchonanthi on leaves of Tarchonanthus littoralis (South Africa); Elsinoe eucalyptorum on leaves of Eucalyptus propinqua (Australia); Exophiala quercina on dead wood of Quercus sp., (Germany); Fusarium californicum on cambium of budwood of Prunus dulcis (USA); Hypomyces gamsii on wood of Alnus glutinosa (Ukraine); Kalmusia araucariae on leaves of Araucaria bidwillii (USA); Lectera sambuci on leaves of Sambucus nigra (Russia); Melanomma populicola on fallen twig of Populus canadensis (Netherlands), Neocladosporium syringae on branches of Syringa vulgarishorus (Ukraine); Paraconiothyrium iridis on leaves of Iris pseudacorus (Ukraine); Pararoussoella quercina on branch of Quercus robur (Ukraine); Phialemonium pulveris from bore dust of deathwatch beetle (France); Polyscytalum pinicola on needles of Pinus tecunumanii (Malaysia); Acervuloseptoria fraxini on Fraxinus pennsylvanica (Russia); Roussoella arundinacea on culms of Arundo donax (Spain); Sphaerulina neoaceris on leaves of Acer negundo (Russia); Sphaerulina salicicola on leaves of Salix fragilis (Russia); Trichomerium syzygii on leaves of Syzygium cordatum (South Africa); Uzbekistanica vitis-viniferae on dead stem of Vitis vinifera (Ukraine); Vermiculariopsiella eucalyptigena on leaves of Eucalyptus sp. (Australia)