|
|
15.10.2022: How Climate Stress Sickens PlantsEsca & Co is actually a stress-induced disease. The responsible fungi can live in the wood for many years without causing symptoms. However, when plants are exposed to climate stress, what happens also in our region with increasing frequency, the fungus can sense this and shifts then to a different behaviour - he kills his host, steals the resources from its corpse, makes sex and runs away (it produces spores). The evolutionary meaning is that the fungus cannot expect much from a moribund host and, thus, needs to search for a new place to stay. The outbreak of Esca & Co is, therefore, steered by chemical signals. In a cooperation between the Institute for Biologically Active Compounds (IBWF) in Kaiserslautern we succeeded to clear up two of these signals. Under stress, ferulic acid accumulates in the wood of the grapevine trunk, because this precursor of lignin cannot be any longer converted. The fungus Neofusicoccum parvum has "learnt", to sense ferulic acid as signal for the ensuing crisis of its host and to respond by secretion of Fusicoccin A. Also Fusicoccin A is a signal. It evokes in grapevine programmed cell death, a type of cellular suicide that is actually meant for defence against biotrophic pathogens. These "modern" pathogens can turn the host cell into a kind of zombie that cannot help providing the intruder with sugar. The economically relevant diseases Grapevine Downy and Powdery Mildew are caused by such smart pathogens. The suicide of the zombie cell is efficient, because it tears also these biotrophic pathogens into death. For the defence against Esca & Co this type of defence is completely outplaced, though. Esca fungis live on cell corpses anyway, in technical terms they are necrotrophs. A host cell that kills itself, is for this fungus a convenient victim, therefore. Thus, Fusicoccin A manipulates plant defence in a way that is bad for the plant, but good for the fungus. We succeeded now to elucidate this sophisticated manipulation by chemical signals and publish this in the journal Plant Cell & Environment. Khattab I, Fischer J, Kazmierczak A, Thines E, Nick P (2022) Hunting the plant surrender signal activating apoplexy in grapevines after Neofusicoccum parvum infection, Plant Cell Environment doi.org/10.1111/pce.14468 - pdf
|
 |
27.07.2022: MikrobenkampagneUm Mikroben zu finden, die im Wurzelraum leben und das Immunsystem der Rebe stärken können, so dass sie Esca & Co besser widerstehen kann, planen für August 2022 eine Sammelkampagne in der gesamten Oberrheinregion. Hier brauchen wir die Hilfe von Winzerinnen und Winzern: wenn Sie in Ihrem Weinberg von Esca befallene Stöcke haben, können Sie uns kontaktieren. Wir entnehmen dann eine kleine Menge (ca. 1 Liter) Erde im Unterstockbereich, als Kontrollprobe Erde von gesunden Reben im selben Weinberg. Natürlich tun wir das sehr vorsichtig und schonend, um ihre wertvollen Rebstöcke nicht zu schädigen. Aus der Erdprobe wird dann die DNS extrahiert und mithilfe modernster Technologie (sogenannter Metagenomik) untersucht. Wir könne dann die Zusammensetzung der Mikrobenflora feststellen, um so "heilende" Mikroben zu finden, die auch in einem heißen und trockenen Sommer, wie er auch dieses Jahr wieder zu erwarten ist, der Pflanze dabei helfen, den Ausbruch des sogenannten apoplektischen Zusammenbruchs (rechts Bild) zu verhindern. Hier können Sie sich anmelden. |
