lecture 7

lecture 7 - 9/13/10 Introductory Plant Pathology BTNY...

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Unformatted text preview: 9/13/10 Introductory Plant Pathology BTNY 301 R. D. Martyn Fall, 2010 Lecture #7 Diseases caused by bacteria RD Martyn, Purdue University 1 Johnson, K.B. 2000. Fire blight of apple and pear. The Plant Health Instructor. DOI: 10.1094/PHI ­ I ­2000 ­0726 ­01 Fire Blight – Erwinia amylovora •  Hosts – ___________________ •  Symptoms – _________________________________ ___________________________________________ RD Martyn, Purdue University 2 1 9/13/10 Fire blight •  Pathogen – ______________. Gram ________, _____ ­shaped bacterium with __________________flagella. •  1° InfecSon Court – _____________ (nectarthodes) •  1° Vector  ­ ________________________ •  Requires epiphySc growth of bacterium on sSgma •  Disease spread – __________________________________ •  Secondary spread via _______________________________ RD Martyn, Purdue University 3 Fire blight •  Disease management –  _____________________(Red Delicious, Golden Delicious; Fuji, Gala & Braeburn are more suscepSble).  ­  _______________________________________________  ­  _______________________________________________  ­  _______________________________________________  ­  _______________________________________________ RD Martyn, Purdue University 4 2 9/13/10 _____________– Disease cycle RD Martyn, Purdue University 5 Kado, C.I. 2002. Crown gall. The Plant Health Instructor. DOI:10.1094/PHI ­ I ­2002 ­1118 ­01 Crown gall – Agrobacterium tumefaciens •  Pathogen: ______________________ •  MoSlity: ____________________ flagella •  Hosts: ____________________________ Walnut Alfalfa Bean Rose Grape RD Martyn, Purdue University 6 3 9/13/10 (The Imperial Vault of Heaven, Beijing, China) Crown gall on Roses RD Martyn, Purdue University 7 Crown Gall •  InfecSon –  A. tumifasciens only infects through ________________ –  Senses specific ______________released during wounding –  ______________ (vir) on the _________ (tumor ­inducing) are expressed resulSng in a long, flexous filament called a__________. RD Martyn, Purdue University 8 4 9/13/10 Crown Gall •  Bacterial cells aeach to wound site by ________ and formaSon of a _____________. •  __________ from the bacterium is transferred into the plant cell through the T pilus and integrates into the plant cell DNA. •  AcSvaSon of addiSonal vir genes results in the plant over ­producing ______________ (auxins, cytokinins) and ________(unique nitrogen source for bacterium) causing abnormal cell division, cell enlargement and uncontrolled cell growth (tumor, gall). RD Martyn, Purdue University 9 Transfer of T ­DNA RD Martyn, Purdue University 10 5 9/13/10 Crown Gall RD Martyn, Purdue University 11 Crown Gall •  Survival –  Survives on the _________________ of plants –  In _____________ •  Spread  ­   ­   ­   ­  _______________________________________ _______________________________________ _______________________________________ _______________________________________ 12 RD Martyn, Purdue University 6 9/13/10 Crown Gall •  Disease management –  Use _______________________________planSng stock –  Use fields previously planted to ____________________ –  Use ____________ crops in rotaSon with suscepSble crop –  Proper ____________________________________ –  _______________________ of infected plants –  ____________________ (A. radiobacter K84 produces the anSbioSc Agrocin ­84 which inhibits DNA replicaSon in A. tumifasciens. –  _________________: Plants engineered with one or more unique genes that prevent A.t. from aeaching to the plant; inacSvate the T ­DNA strand or prevent expression of the T ­ DNA genes that synthesize auxins and cytokinins. RD Martyn, Purdue University 13 Citrus canker – Xanthomonas axonopodis pv. citri Goewald, T.R. 2000. Citrus canker. The Plant Health Instructor. DOI: 10.1094/PHI ­I ­2000 ­1002 ­01 •  •  •  •  Pathogen: ___________________ MoSlity: _____________________ Produces yellow colonies on agar. Hosts: _____________________ (orange, lime, lemon, grapefruit, tangerine, etc.) J. Bacteriol.107:295 RD Martyn, Purdue University 14 7 9/13/10 •  InfecSon Citrus Canker –  Requires ________________________ (82 to 86 °F) –  1° infecSon court: __________________ –  Spread: ___________________________ Leaf stomate w/ bacteria RD Martyn, Purdue University 15 Citrus Canker –  2° infecSon court: __________ (pruning, thorns, etc) –  __________ (leaf miners) RD Martyn, Purdue University 16 8 9/13/10 Citrus Canker •  Symptoms –  Leaf lesions, _____________ (raised margin / sunken center) –  Leaf lesions have _______________________ RD Martyn, Purdue University 17 Citrus Canker –  Fruit lesions –  Stem Lesions RD Martyn, Purdue University 18 9 9/13/10 Citrus Canker •  Different ____________ (pv) of X. axonopodis –  X. axonopodis pv. citri (AsiaSc strain or Canker A strain) is most severe. –  ___________ are disSnguished from each other by their differenSal disease reacSons on different hosts; _________ analysis; __________________; and ___________________ sensiSvity. RD Martyn, Purdue University 19 Citrus Canker RD Martyn, Purdue University 20 10 9/13/10 Disease Management •  _______________ and ________________ –  Local or regional quaranSnes for import of fruit and root stock –  Plant only cerSfied disease ­free nursery stock –  Proper disinfecSon of workers clothes, tools, equipment, harvesSng boxes, etc. DecontaminaSon staSon next to a commercial citrus grove RD Martyn, Purdue University 21 Disease Management •  CulSvar selecSon –  Highly resistant: Calamondin (C. mitus); Kumquats (Fortunella spp.) –  Resistant: Mandarins (C. reXculata) –  Less suscepSble: Tangerines, Tangors, Tangelos, Valencia oranges; Sour oranges (C. auranXum) –  SuscepSble: ______________ Navels (all selecSons), Limes (C. laXfolia) –  Highly suscepSble: _____________ (C. paradisi); Mexican/ Key lime (C. auranXifolia); Lemons (C. limon) RD Martyn, Purdue University 22 11 9/13/10 Disease Management •  _________________________ –  ____________________ –  ______________________________ (dry season) RD Martyn, Purdue University 23 Disease Management •  _____________________ –  Spraying with _______________ bactericides. Up to as many as 6 or more sprays may be necessary per season RD Martyn, Purdue University 24 12 9/13/10 Disease Management •  _______________ (1910, 1933, 1980s & 1990s) –  Infected commercial trees are uprooted and burned –  Infected ‘dooryard’ trees are removed RD Martyn, Purdue University 25 Disease Management •  EradicaSon – Urban spread –  “_________________” (Mar 2000) –  ______________________ •  SuscepSble trees planted in 144 secSons / sq. mile RD Martyn, Purdue University 26 13 9/13/10 Citrus Canker – What went wrong? •  2000 – Circuit Court Judge issues injuncSon on cusng trees. AddiSonal liSgaSon from home owners halt eradicaSon program for 18 month. RD Martyn, Purdue University 27 Citrus Canker – What went wrong? •  2000 – Circuit Court Judge issues injuncSon on cusng trees. AddiSonal liSgaSon from home owners halt eradicaSon program for 18 month. •  2001 – 2004 hurricanes hit Florida RD Martyn, Purdue University 28 14 9/13/10 Citrus canker today threatens Florida’s $8 billion citrus industry 2006 USDA declared eradicaSon no longer possible; abandons program. Citrus canker present throughout southern and south ­central Florida. Total # trees destroyed – 2 million Total cost to Federal & State –  EradicaSon program: $600 million –  CompensaSon program: $300 million •  EsSmated on ­going yearly costs: $250 million •  •  •  •  RD Martyn, Purdue University 29 Some Common Bacterial Plant Diseases Bacterial spots and blights Pseudomonas syringae pv. phaseolina (_____________________) “ “ pv. tomato (______________________) Xanthomonas compestris pv. phaseoli (______________________) “ “ pv. oryzae (________________________) Acidovorax avenae subsp. citrulli (__________________________) Bacterial wilts Erwinia tracheiphila (______________________) Ralstonia solanacearum (___________________________) Pantoea (Erwinia) stewarXi (________________________) RD Martyn, Purdue University 30 15 ...
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