Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Seit Februar 2021 bietet Wolfgang Brandt, ehemaliger Leiter der Arbeitsgruppe Computerchemie am IPB, sein Citizen Science-Projekt zur Pilzbestimmung an. Dafür hat er in regelmäßigen Abständen öffentliche Vorträge zur Vielfalt…
Horbach, R.; Navarro-Quesada, A. R.; Knogge, W.; Deising, H. B.;When and how to kill a plant cell: Infection strategies of plant pathogenic fungiJ. Plant Physiol.16851-62(2011)DOI: 10.1016/j.jplph.2010.06.014
Fungi cause severe diseases on a broad range of crop and ornamental plants, leading to significant economical losses. Plant pathogenic fungi exhibit a huge variability in their mode of infection, differentiation and function of infection structures and nutritional strategy. In this review, advances in understanding mechanisms of biotrophy, necrotrophy and hemibiotrophic lifestyles are described. Special emphasis is given to the biotrophy-necrotrophy switch of hemibiotrophic pathogens, and to biosynthesis, chemical diversity and mode of action of various fungal toxins produced during the infection process.
Publikation
Haapalainen, M.; Engelhardt, S.; Küfner, I.; Li, C.-M.; Nürnberger, T.; Lee, J.; Romantschuk, M.; Taira, S.;Functional mapping of harpin HrpZ of Pseudomonas syringae reveals the sites responsible for protein oligomerization, lipid interactions and plant defence inductionMol. Plant Pathol.12151-166(2011)DOI: 10.1111/j.1364-3703.2010.00655.x
Harpin HrpZ is one of the most abundant proteins secreted through the pathogenesis‐associated type III secretion system of the plant pathogen Pseudomonas syringae. HrpZ shows membrane‐binding and pore‐forming activities in vitro, suggesting that it could be targeted to the host cell plasma membrane. We studied the native molecular forms of HrpZ and found that it forms dimers and higher order oligomers. Lipid binding by HrpZ was tested with 15 different membrane lipids, with HrpZ interacting only with phosphatidic acid. Pore formation by HrpZ in artificial lipid vesicles was found to be dependent on the presence of phosphatidic acid. In addition, HrpZ was able to form pores in vesicles prepared from Arabidopsis thaliana plasma membrane, providing evidence for the suggested target of HrpZ in the host. To map the functions associated with HrpZ, we constructed a comprehensive series of deletions in the hrpZ gene derived from P. syringae pv. phaseolicola, and studied the mutant proteins. We found that oligomerization is mainly mediated by a region near the C‐terminus of the protein, and that the same region is also essential for membrane pore formation. Phosphatidic acid binding seems to be mediated by two regions separate in the primary structure. Tobacco, a nonhost plant, recognizes, as a defence elicitor, a 24‐amino‐acid HrpZ fragment which resides in the region indispensable for the oligomerization and pore formation functions of HrpZ.
Publikation
Klopotek, Y.; Haensch, K.-T.; Hause, B.; Hajirezaei, M.-R.; Druege, U.;Dark exposure of petunia cuttings strongly improves adventitious root formation and enhances carbohydrate availability during rooting in the lightJ. Plant Physiol.167547-554(2010)DOI: 10.1016/j.jplph.2009.11.008
The effect of temporary dark exposure on adventitious root formation (ARF) in Petunia×hybrida ‘Mitchell’ cuttings was investigated. Histological and metabolic changes in the cuttings during the dark treatment and subsequent rooting in the light were recorded. Excised cuttings were exposed to the dark for seven days at 10°C followed by a nine-day rooting period in perlite or were rooted immediately for 16 days in a climate chamber at 22/20°C (day/night) and a photosynthetic photon flux density (PPFD) of 100 μmol m−2 s−1. Dark exposure prior to rooting increased, accelerated and synchronized ARF. The rooting period was reduced from 16 days (non-treated cuttings) to 9 days (treated cuttings). Under optimum conditions, despite the reduced rooting period, dark-exposed cuttings produced a higher number and length of roots than non-treated cuttings. An increase in temperature to 20 °C during the dark treatment or extending the cold dark exposure to 14 days caused a similar enhancement of root development compared to non-treated cuttings. Root meristem formation had already started during the dark treatment and was enhanced during the subsequent rooting period. Levels of soluble sugars (glucose, fructose and sucrose) and starch in leaf and basal stem tissues significantly decreased during the seven days of dark exposure. This depletion was, however, compensated during rooting after 6 and 24h for soluble sugars in leaves and the basal stem, respectively, whereas the sucrose level in the basal stem was already increased at 6 h. The association of higher carbohydrate levels with improved rooting in previously dark-exposed versus non-treated cuttings indicates that increased post-darkness carbohydrate availability and allocation towards the stem base contribute to ARF under the influence of dark treatment and provide energy for cell growth subject to a rising sink intensity in the base of the cutting.
Publikation
Serra, P.; BANI HASHEMIAN, S. M.; PENSABENE-BELLAVIA, G.; Gago, S.; DURAN-VILA, N.;An artificial chimeric derivative of Citrus viroid V involves the terminal left domain in pathogenicityMol. Plant Pathol.10515-522(2009)DOI: 10.1111/j.1364-3703.2009.00553.x
The recently described Citrus viroid V (CVd‐V) induces, in Etrog citron, mild stunting and very small necrotic lesions and cracks, sometimes filled with gum. As Etrog citron plants co‐infected with Citrus dwarfing viroid (CDVd) and CVd‐V show synergistic interactions, these host–viroid combinations provide a convenient model to identify the pathogenicity determinant(s). The biological effects of replacing limited portions of the rod‐like structure of CVd‐V with the corresponding portions of CDVd are reported. Chimeric constructs were synthesized using a novel polymerase chain reaction‐based approach, much more flexible than those based on restriction enzymes used in previous studies. Of the seven chimeras (Ch) tested, only one (Ch5) proved to be infectious. Plants infected with Ch5 showed no symptoms and, although this novel chimera was able to replicate to relatively high titres in singly infected plants, it was rapidly displaced by either CVd‐V or CDVd in doubly infected plants. The results demonstrate that direct interaction(s) between structural elements in the viroid RNA (in this case, the terminal left domain) and as yet unidentified host factors play an important role in modulating viroid pathogenicity. This is the first pathogenic determinant mapped in species of the genus Apscaviroid.