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Erwinia, Brenneria, Pantoea, and Pectobacterium (facultative anaerobes) General: 1. Heterogenous: generally clas

Erwinia, Brenneria, Pantoea, and Pectobacterium (facultative anaerobes) General: 1. Heterogenous: generally classified into 4 groups; 2. Numerous commodities (apples, potatoes, cricket bat trees, cereal crops, etc.). Unusual Erwinias:

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Erwinia, Brenneria, Pantoea, and Pectobacterium (facultative anaerobes) General: 1. Heterogenous: generally clas

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  1. Erwinia, Brenneria, Pantoea, and Pectobacterium (facultative anaerobes) • General: • 1. Heterogenous: generally classified into 4 groups; • 2. Numerous commodities (apples, potatoes, cricket bat trees, cereal crops, etc.)

  2. Unusual Erwinias: • a. E. uredovora (synonyms: E. ananas pv.uredovora; Pantoea ananas); parasite of rust fungi – Biocontrol??? • b. E. tracheiphila and E. stewartii - overwinter in beetles.

  3. Wide range of plant diseaseswilts, blights, cankers, dieback, leaf and fruit spotsdiscoloration of woody tissuePantoea agglomerans(E. herbicola): human pathogen.

  4. Pantoea agglomerans: (syn. E. herbicola) • Usually a saprophyte • Epiphytic on many plants (leaves and flowers), • Problem in isolating E. stewartii from corn • Often found associated with fireblight (E. amylovora) • Reduces fireblight severity.

  5. 4. Identification • 1. Gram-negative • 2. ** Peritrichously flagellated, except E. stewartii • 3. ** aerobic or facultative anaerobe (ex. carotovora pv. atroseptica) • 4. optimum growth - varies so much within genus: E. carotovora pv. atroseptica (about 20C) E. carotovora pv. carotovora (28C)

  6. 5. oxidase negative; catalase positive • 6. % G+C 50-58 • 7. Diagnosis: disease symptoms, colony morphology on specific media; ferments carbohydrates - Erwinia spp. Is the likely pathogen. • 8. Selective media; Miller & Schroth; CVP.

  7. Taxonomy: A. Amylovora and Brenneria groups: a. cause dry rots or wilt symptoms b. no pectic enzymes or yellow pigments

  8. c. examples: • E. mallotivora: small tree in Japan • B. nigrifluens: bark canker of walnut • B. quercina: drippy nut of oak (California) • B. quercinia pv. rubrifaciens phloem canker of walnut - (California) • E. alni: Bark cankers of alder (Alnus) in Italy.

  9. B. salicis: watermark disease of willow, discolors wood used to make cricket bats (England). • E. billingiae: stem cankers, blossoms and immature fruits primarily from rosaceous trees. • Often in association with plant pathogens • considered secondary invaders. • Recently described species - named after Eve Billing.

  10. E. amylovora: • 1. Fireblight disease of apples, pears, (Rosaceae) etc. • 2. Serious throughout the world; bacteria are commonly resistant to antibiotics (Streptomycin & Oxytetracycline). • 3. Flowers are most common site of infection.

  11. Fireblight – Apple – Erwinia amylovora

  12. epiphytic populations on stigma precedes infection. Warm temps during bloom (>15 C) • pollinating insects promote establishment and growth of bacteria. Epiphytic bacteria also grow on anthers and hypanthium (nectary). • Stigmas: protected, nutrient rich, hydrated environment Epiphytes (E. a) may colonize at populations greater than 106 CFU/stigma. • 5. E. amylovora colonizes stigma, cells are washed to the hypanthium (nectarthodes) where infection occurs. Sugar conc. in nectar may reach 60%. After rain, may be <2%.

  13. 6. E. amylovora cells detectable in blossoms after temp reaches 15 C (60 F). Accumulated degree hours above 18.3 C (65 F) resulted in two predictive models: MARYBLYT and COUGARBLIGHT • MARYBLIGHT: calculates degree hours above 18.3 C and a threshold value of 110 cumulative degree hours from blossom pink stage. Most popular of the models. • COUGARBLIGHT; Sums degree hours above 15.5 C for 4 days.

  14. Fireblight – Apple – Erwinia amylovora

  15. Fireblight – Apple – Erwinia amylovora

  16. Fireblight – Apple – Erwinia amylovora

  17. Fireblight – Apple – Erwinia amylovora

  18. Fireblight – Apple – Erwinia amylovora

  19. Fireblight – Apple – Erwinia amylovora

  20. 7. Biological control: Suppression of fire blight by antagonistic bacteria. • Pseudomonas fluorescens strain A506 ( BlightBan A506). • Erwinia herbicola strain C9-1 (Pantoea agglomerans, EHC9-1) received an experimental permit from EPA in 1998. • A)To be effective, stigma must be colonized at 105 to 106 CFU. Competitive exclusion is probably the mode of action.

  21. A506 suppresses growth 72 hr before inoculation with E. amylovora but not when co-inoculated at the same time. 40-60% reduction in blossom blight with 2 application of A506. • EhC9-1 produces two antibiotics that inhibit E. amylovora. Also competes for sites and nutrient sources. Treatment with EhC9-1 reduced fire blight between 50-80 %; similar to antibiotic sprays.

  22. Recommendation: Apply bacterial antagnostics twice between 25% and 90% bloom. • Insects, mostly bees, disseminate antagonistic bacteria from colonized to noncolonized blossoms. • Erwinia herbicola (Eh1087), an epiphyte (New Zealand) produces a B-lactam antibiotic. In experimental stage of development.

  23. f. E. tracheiphila: (Bacterial wilt of cucurbits) serious problem in cucurbits; muskmelon and cucumbers are very susceptible; • Squash, moderately susceptible, pumpkin, moderately resistant, watermelon, nearly immune.

  24. Overwinters and vectored by 12-spotted and striped cucumber beetles. Bacteria in feces - enter through wounds. • Control: control beetles by spraying insecticides. • Diagnosis: cut stem - viscous strands may extend upwards of 4-6 inches. Pull strands over petri plate. Difficult to keep in culture except in lyophil

  25. Bacterial wilt – Muskmelon – E. tracheiphilia

  26. Bacterial wilt – Muskmelon – E. tracheiphilia

  27. Bacterial wilt – Muskmelon – E. tracheiphilia

  28. Bacterial wilt – Muskmelon – E. tracheiphilia

  29. Bacterial wilt – Muskmelon – E. tracheiphilia

  30. Bacterial wilt – Muskmelon – E. tracheiphilia

  31. Bacterial wilt – Squash – E. tracheiphila

  32. Bacterial wilt – Squash – E. tracheiphilia

  33. Erwinia pyrifoliae: Recently described pathogen from Asian pears in Korea. Very similar to E. amylovora (the same ?).

  34. B. Herbicola group: • a. yellow pigments (usually) • b. opportunistic pathogens of man; many are nonpathogenic plant epiphytes • c. examples:

  35. E. ananas pv. ananas: (Pantoea citrea) Pink disease of pineapple • Symptoms not recognized until fruit is cored and canned. • Diagnosis: sample cans of fruit • Zero tolerance: positive diagnosis: entire lot must be destroyed (lot = 37,000 cans).

  36. E. ananas pv. uredovora: parasite on urediospores of leaf rust (Puccinia graminis) of wheat. Needs to be more throughly researched - possible biocontrol for leaf rust?

  37. E. herbicola pv. herbicola: galls on Gypsophila (baby breath) • E. herbicola pv. milletiae: Wisteria tree, mostly galls (Japan). • Enterobacter pyrinus: Brown leaf spot disease of pear trees (Korea).

  38. E. stewartii - (syn: P. stewartii or P. s. subsp. stewartii) Stewarts wilt of corn (political disease / trade barrier) Vector: Corn flea beetle - Bacteria overwinter in insect Beetles are very efficient vectors • Imidacloprid seed treatment reduced flea beetles and disease

  39. Maize and sweet maize (principal hosts); severe losses to corn crop in 1930's • North, Central, South America, Europe and Asia • Seedborne - but rare. Seed transmission (95% CI) was 0.22% or about 2 positive plants from 1,000 E. stewartii infected kernels.

  40. Excellent resistance in most hybrids - Since 1995, Stewart=s wilt has increased in Kansas and other areas in the corn belt. Disease forecasting based on average winter temperature Cold winter - fewer beetles survive. Sum of mean temperatures for December, January & February > 100 C - - large number of insects survive. Cold winters: Sum of mean temperatures < 85 C.

  41. A "BIG" problem in international shipments of seed and feed grains • Over 100 countries require a phytosanitary certificate that grain is free of Stewart's wilt. Political disease of corn. Also, a false positive diagnosis in sorghum is a BIG concern.

  42. Stewart’s wilt – Corn –Pantoea stewartii

  43. Stewart’s wilt – Corn – Pantoea stewartii

  44. Pantoea stewartii subsp. indologenes: (indolum, indole: gennao, to produce Strains are Athought@ to cause leaf spot on foxtail and pearl millet. Only 8 strains tested and were received as E. herbicola.

  45. Carotovora group: • Erwinia to Pectobacterium • (Hauben, L., et al (1998). Syst. Appl. Microbiol 21:384-397.

  46. Produce pectolytic enzymes macerate cell walls of host plants (mainly soft rots in storage). Pathogenicity: bacteria produce exoenzymes: pectate lyase (Pel), polygalacturonase (Peh), cellulase (Cel), protease (Prt) - degrade cell walls of plants.

  47. Great economic importance: both storage and in-field losses

  48. Predisposing causes such as frost and mechanical injury, • other bacteria and fungi may enhance soft rot infections. • e.g. blackleg of potatoes in Montana

  49. E. carotovora pv. carotovora: • many hosts affected; • warm temperature organism, • many serotypes (30?), • commonly found in soil. • Causes soft rot of potato tubers and pathogenic to numerous crops. • Important in storage of vegetables.

  50. E. carotovora pv. atroseptica: • Important in blackleg disease of potato (cool regions - 20C). • An important disease of potato.

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