Phytopathogens III Flashcards
Mikroorganismen entschärfen pflanzliche Gifte
*MO in Darmtrakt von Schafen “entgiften” Isoflavonoide (Klee)
*Burkholderia schützen Stinkwanzen vor organophosphoren Pestiziden (OP)
*kann OP abbauen -> Bakterium wird von Insekt aufgenommen und metabolisiert im Insekt OPs
=> symbiont. Bakterien fördern Resistenzen gegen Pestizide
Weitere Funktionen von MO
- können den Fortpflanzungsmodus ändern (Wolbachia)
- Mate choice beeinflussen
- Schutz gegen natürliche Feinde wie Viren, Protozoa und parasitische Insekten bieten
(z. B. Blattlaus Acyrthosiphon pisum, Parasitoid: Aphidius ervi, Bakterien: Hamiltonella defensa)
Virus schützt Parasitoide vor Immunreaktion des Hosts
- Parasitoide Wespe legt Eier in Wirt -> Freisetzen von polyDNAviren mit Eiern
- Virus mit mehrere Segmenten von dsDNA und mit Introns
- Virus blockt Akkumulation von Host Hämozyten an Parasitoideiern (Zerstören der Zellen), beeinflusst Biogenese von Phenoloxidase und manipuliert Wirtentwicklung
Virus ermöglicht es, dass ein Gras in heißer Erde wachsen und überleben kann
- Gras wächst auf Bodentemperatur von >50°C
- Pflanze benötigt Pilzendophyten - Curvularia protuberata um zu überlegen
- Pilz benötigt Virus (Curvularia thermal tolerance virus) um thermotolerance effect abzubilden
Einfluss von MO auf mate choice
- C-Flies: reared on corn meal-molasses-yeast agar medium
- low proportion of Lactobacillus plantarum
- S-Flies reared on starch-based medium
- high proportion of Lactobacillus plantarum
- preference for mates reared on the same diet
- S-Flies: more abundant male recognition cue than C-flies
- difference in abundance of 7,11 heptacosadiene abolished after treatment of flies with antibiotics
- mate preference abolished after treatment with antibiotics
- different microbiome in C- and S-flies
- three alternate mechanisms:
a) bacteria themselves produce molecules detected by the flies via chemoreception; flies habitate to odors produced by their own commensal bacteria, but discriminate against ‘foreign’ odors
b) bacteria may alter CH profile directly by utilizing them as a carbon source or as a substrate for a degradative enzyme. Under this scenario the relevant bacteria would have to be located on the fly surface, presumably near sites of CH release
c) bacteria may alter CH profile indirectly by affecting CH biosynthesis
Einfluss von MO durch Aggregation
- Schistocera gregaria (descert locust)
- aggregation pheromone released from fecal pellets
- germ-free fecal pellets
a) no guaiacol or
b) low quantities of guaiacol - adding Pantoea agglomerans to feces
- > high quantities of guaiacol
Transfer of Wolbachia
- Vertical transfer
- > eggs, only through cytoplasm
- Horizontal transfer
a) Transmission into plant-sucking insects via W.-infected plants and from infected plant-sucking insects back to as yet uninfected plants
b) Transmission into parasitoids via W.-infected host insects and from infected parasitoids back to as yet uninfected host insects
W. benefits oogenesis
*Bedbugs
> provides Vitamin B & biotin
> without W.: disturbed egg development
*A. tabida
> provides apoptosis of nurse cells
> without W: no normal oogenesis
BT
- toxisches Protein: Cry-Protein -> assoziert mit Bakteriensporen als Endotoxin in Sporen
- an Sporen außen auch Exotoxine
- natürlicherweise im Boden und an Pflanzen
Cry Protein: mode of action
= inactive protoxin
= conversion of the protoxin into the active toxin requires the combination of a slightly akaline phH and the action of a specific protease found in the insect gut
= the active toxin binds to protein receptors on the insect gut epithelial cell membrane
= the toxin forms an ion channel between the cell cytoplasm and the external environment, leading to loss of cellular ATP and insect death
BT Toxin: Toxizität?
*toxin is insertetd in gut epithelial cell membranes of the insect and forms an ion channel between the cell cytoplasm and the external environment, leading to loss of cellular ATP and insect death
