Biological Derivatives for Plant Disease Control

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Biological Derivatives for Plant Disease Control

• Ent 547 Fundamentals of Biological Control
• Fall 2005

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Biological Derivatives

• Sources of materials
• Bacteria
• Fungicides
• Fungi
• Fungicides
• Nematicides
• Viruses
• Transgenic Plants
• Plants
• Transgenic Plants
• Compost Teas and Extracts

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Mode of Action of Biological Derivatives

• Biocidal Pesticides
• Maxim
• Strobilurins
• Inducers of Plant Resistance
• Derivatives of the Hrp cluster
• Transgenic Plants (viral products, chitinase)
• Compost Teas and Extracts
• Mixture of site exclusion, antibiosis, and
  induced resistance

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Biocidal Pesticides

• Natural or synthetic chemistries that are based
  on naturally occurring bioactive metabolites
• There are numerous examples but only a few has
  been developed into products
• Potential for discovery and development of new
  chemistries
• Standard approach
• Bioinformatics

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From http//helios.bto.ed.ac.uk/bto/microbes/pen
icill.htm

• Streptomyces
• ?-methylene-?-alanine - slight activity against
  velvet leaf, antibacterial, also found in sponges
• cis-2-amino-1-hydroxycyclobutane-1-acetic acid -
  chlorosis and growth retardation, antibacterial
• Herbicidins (A, B, E, F, G) - kills many grasses
  but not rice, A control of Xanthomonas oryzae.
  Many dicots affected
• hydantocidin - a nitrogen containing herbicide
  of monocots and dicots with no antifungal or
  antibacterial activity

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Bioactive Metabolites

• Fusarium
• 3-hydroxycyclobut-3-ene-1,2-diol F. moniliforme
  - potent herbicide, locks mitosis similar to
  colchicine
• Food borne toxins
• Nocardia
• Soilborne actinomycete that can cause a rare
  disorder of the lungs, brain, or skin in
  immunocompromised individuals
• formycin - a nucleoside

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Bioactive Metabolites

• Salicylic acid - induced resistance
• 2-fluoroglucinol - Pseudomonas aureofaciens
• phenazine - Pseudomonas fluorescens
• Auxigro - gamma amino butyric acid, Fusarium
• Upcoming new materials from basidiomycetes -
  Abound

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Disease Sour skin of onions Bacterium
Burkholderia cepacia First described by Walter
Burkholder in 1950
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Maxim Burkholderia cepacia

• Aoki et al., 1991
• Tobacco cultivated on rice paddies lower
  incidence of bacterial wilt (Ralstonia
  solanacearum)
• Isolated antagonists (B. cepacia)
• 2-keto-D-gluconic acid - intermediary in
  pectolytic enzyme synthesis
• Also inhibited P. putida, P. syringae, P.
  lachrymans, and P. aeruginosa (pectolytic)

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Burkholderia cepacia study

• Gill and Cole, 1991
• Mushroom grower in New Zealand switched to
  Agaricus bitorquis from A. bisporus
• Grow at higher temperatures - less virus disease
• Cavity rot
• Isolated B. cepacia
• McLoughlin et al., 1992
• Inhibition sunflower wilt caused by Sclerotinia
  sclerotiorum (increased seedling emergence)
• Pyrrolnitrin, aminopyrrolnitrin,
  monochloroaminopyrrolnitrin
• UV-light mutants did not suppress disease

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Burkholderia cepacia story

• Hebbar et al., 1992
• efficient root colonizer of maize, need a minimum
  of 30 bacterial cells per seed
• Parke et al., 1990s
• control of Aphanomyces and Pythium root rot of
  peas
• 1992 Patent
• Maxim

Burkholderia, Friend or Foe? http//www.apsnet.org
/online/feature/BurkholderiaCepacia/Top.html
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• Maxim- fludioxonil (phenylpyrrole)
• Broad-spectrum activity against seed-borne and
  soil-borne diseases (Ascomycetes, Deuteromycetes,
  and Basidiomycetes).
• Fusarium, Rhizoctonia, and Helminthosporium and
  weakly pathogenic fungi of the genera Penicillium
  and Aspergillus.
• Registered for corn, sweet corn, sorghum, soybean

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Strobilurus tenacellusThe Pine Cone Fungus

• Strong inhibition of many fungi in vitro
• Greenhouse tests with plant pathogens were
  disappointing
• The antibiotic Strobilurin A is light sensitive

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• Chemical alteration
• Broad spectrum antifungal agent
• Quick acting
• Leaf inhabiting fungi
• Quickly degraded in soil, water, and plant tissue

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Strobilurin Fungicides

• A series of compounds that have cytochrome B
  (Ubiquinol oxidase) binding activity.

Fluoxastrobin
fenamidone
azoxystrobin
picoxystrobin
http//www.verbutin.com/strobilurines_main.htm
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New Technologies?
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Induced Plant Resistance

• Induced Plant Resistance is a phenomenon where
  prior exposure to microorganisms or chemicals
  enables the plant to be resistant to infection by
  similar and dissimilar pathogens
• Types
• Cross protection a direct antagonism
  (antibiosis, site and nutrient competition,
  parasitism) by one organism against another in
  the host tissue
• Systemic Acquired Resistance indirect action
  where an organism stimulates the plants defense
  mechanisms

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Inducers

• Organisms that serve as inducers are
• Nonpathogenic or weakly pathogenic
• However, for most cases, they are strong
  pathogens in other hosts
• Four Examples of CP/IR
• Virus cross protection Citrus tristeza virus,
  Tobacco mosaic virus
• Fungal cross protection Gaeumannomyces graminis
  var. tritici/Phialophora graminicola in
  grass/wheat rotations in England.
• Multiline and variety mixtures
• Mycorrhizae

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(No Transcript)
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Citrus Tristeza Virus (CTV)

• First introduced in the 1920s in Brazil
• Spread to Argentina, Uruguay
• Search for mild strains in moderate and severely
  infected orchards in 1960s
• Selected 1 of 45 strains.
• Inoculated bud wood
• Graft onto CTV tolerant rootstocks

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The Hypersensitive Reaction

• rapid necrosis of plant tissue
• accumulation of phenolics and phytoalexins
• rapid death of the invading microorganism
• associated with avr genes
• Bacterial determinants
• may be initiated by hrp genes
• Type III secretion system

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Secretory Systems in Bacteria
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Systemic Acquired Resistance

• Inoculation of pathogenic bacteria or fungi
  causes lesions
• Plant becomes increasingly resistant to a wider
  range of pathogens

• Involves
• Antimicrobial compounds
• Enzymes chitinases, glucanases
• Lignification
• Pathogenesis related proteins
• Phytoalexins

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Examples of Systemic Acquired Resistance (SAR) or
Induced Resistance

• Viswanathan and Samiyappan. 2002. Induced
  systemic resistance by fluorescent pseudomonads
  against red rot disease of sugarcane caused by
  Colletotrichum falcatum. Crop Protect. 211-10.
• Spencer, M., et al. 2003. Induced defence in
  tobacco by Pseudomonas chlororaphis strain O6
  involves at least the ethylene pathway. Physiol.
  Molec. Plant Pathol. 6327-34.

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The Harpin Story

• Steven V. Beer
• Cornell University, Ithaca, NY
• Erwinia amylovora
• Fireblight disease

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Pathogenicity Islands

• Genes for pathogenicity and hypersensitivity are
  linked
• The hypersensitive reaction is controlled by a
  series of genes
• One of these genes, cloned into E. coli
• Messenger, Eden BioSciences, 5 11.5 g/acre.

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Transgenic Plants

• Introduction of a new gene
• Agrobacterium mediated
• Biolistics
• Pollen transformation
• Electroporation
• Disease resistance genes
• Coat protein gene from viruses
• Chitinase gene

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Compost Teas and Extracts

• Compost extracts are water extracts of a variety
  of compost materials that can be used as a crop
  protection tool
• Extraction continuous leaching for hours to days
• Additives molasses, seaweed extract, algae,
  yeast
• Microbial enrichment

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Compost Extracts
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Compost Extracts Mechanisms

• Induced resistance
• Inhibition of spore germination
• Antagonism
• Competition

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Compost Teas

• Compost teas are fermentations where beneficial
  microorganisms are grown supplemented with food
  sources such as molasses, kelp, rock dust, humic
  and fulvic acids.
• May be an aerobic or anaerobic process.

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There are Still Questions

• Inoculating compost teas with specific organisms?
• Aerobic or non-aerobic?
• Human health issues?
• Reproducibility?

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Summary

• Derivatives for organisms for disease control
  include
• Bioactive metabolites
• Plant pathogens
• Non-pathogens
• Plant resistance metabolites
• Genes from plant pathogens

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Microbial Biological Control Summary

• Use of the biological control organisms directly
  for disease and pest management
• Use of derivatives of the biological control
  organisms
• Direct
• Indirect induced systemic resistance