Bacteria 3 Flashcards
characteristic s of plasmid
help bacteria to survive stress
Usually carry genes encoding adaptive traits:
-Antibiotic resistance -Pathogenicity factor -Ability to exploit particular niches -Production of conjugation tubes
take enegy to replicate it
Why keep plasmids?
Chromosomal mutations more costly
Pass quickly through population
Evolutionary cost-reduction
three gene that important for agrobacterium tumefacience of Ti plasmid
auxin syntheses
cytokinin syntheses
poine syntheses(food for bacteria)
What other roles can plasmids have in plant pathology?
Bactericide resistance? Copper (Cu++) and antibiotic resistance
Two antibiotics
Streptomycin – kills, foliar spray
-use approved for 12 plant species -high concentrations can be phytotoxic to plants
Primary use (90%) for fireblight – Erwinia amylovora
Oxytetracycline - inhibits growth, foliar spray -can be used injected internally in plants -injection labor intensive and costly
two types of resistance erwinia
- Mutation in the chromosomal gene rpsL which prevents streptomycin
from binding to its ribosomal target - Inactivation of streptomycin by an enzyme encoded by strA and strB
found on a plasmid.
Two Vector-Borne Bacteria
Facultative and Obligate insect transmission
characteristics of Obligate insect transmission
reduce genome
phloem specific pathogen smaller than xylem because phloem is nutrient rich
Genome degradation
Pseudomonas syringae
gram -, able to culture, 6.5Mb
Xylella fastidiosa
2.7 Mb Yes Xylem Gram -
symptom
Leaf Scorch
Spiroplasma citri
Spiroplasma kunkelii
1.8 Mb Yes Phloem Mollicute
Candidatus Liberibacter solanacearum
1.2 Mb No Phloem Gram +
Candidatus Phytoplasma asteris
0.8 Mb No Phloem Mollicute
Phytoplasmas
infect their plant and insect vector hosts, and have effects on both. So far none have been cultured.
Spiroplasmas
have diverged from gram-positive eubacteria, and belong to the Genus Spiroplasma within the
Class Mollicutes.\
can be cultured in vitro.
