Endophytes: biocontrol killers? - PowerPoint PPT Presentation

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Endophytes: biocontrol killers?

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  1. Endophytes: biocontrol killers? Sarah Dodd, Daniel Than, Stanley Bellgard and Chris Winks (LCR) Rebecca Ganley (Scion) Trevor James (AgR)

  2. Endophytes • All plants are infested with microbes • Symptomless • Epiphytes/Endophytes • Balanced status of symbiosis • = Majority • Disease • Pathogens • Unbalanced status of symbiosis

  3. Endophyte/Plant relationship • Endophyte gains • shelter and nutrients • Plant cost • nutrients and resources • (e.g. more susceptible to pests and diseases: BCAs) • Plant gains • Growth promotion • (enhanced nutrient uptake) • Increased tolerance to harsh environments • (e.g. drought tolerance) • Induced Resistance to pests and diseases (BCAs)

  4. Endophytes – weeds and weed biocontrol • Harry Evan’s (2007) proposed: • Weediness: Endophytes influence the fitness of a plant and therefore its invasiveness • Biocontrol: Endophytes interact with plants and/or biocontrol agents either enhancing or reducing their activity

  5. Microbial interactions • Pathogens • Endophytes/epiphytes Antibiosis Parasitism Competition Cell lysis

  6. Microbe interactions – under the microscope

  7. Weed / Endophyte systems under investigation in NZ Sclerotinia on Californian thistle Phoma on Old Man’s Beard Wilding Ginger Privet Pampas

  8. Sclerotinia on Californian thistle- a mycoherbicide • 1. Kills entire plant • 2. Partially kills plant • Plant recovers • 3. No effect on plant

  9. Aim • To identify microbes that influence the success/failure of a pathogen biocontrol agent • To ultimately manipulate interactions to improve consistency of weed biocontrol activity

  10. Progress: step 1determine population variation Roots, shoots, flowers & seeds

  11. Methods - to identify endophytes • Culturing • isolate & identify key endophyte fungi ● DGGE - DNA profile comparisons - endophyte fungi and bacteria - DNA sequence to identify bands (microbes)

  12. Culturing – isolation and identification

  13. Molecular -DGGE • Samples are all assessed and bands(microbes) identified • Variability between tissues/plants/fields has been assessed

  14. Testing influence of endophytes • Glasshouse trials – assess disease development a) BCA + key endophyte b) BCA - key endophyte

  15. Preliminary glasshouse trials • Can endophytes influence Sclerotinia disease? • No influence • Enhanced Sclerotinia disease • Reduced Sclerotinia disease (e.g. Colletotrichum sp.)

  16. Summary • We now have evidence to support the theory that endophytes DO influence the activity of pathogen biocontrol agents

  17. The Future • Sclerotinia on Cali thistle • Identify key bacterial endophytes • Continue glasshouse testing • Identify key endophyte modes of action • Improve pathogen biocontrol agent activity • Other plant systems • Identify key endophytes and test in glasshouse • Endophytes and insect BCAs

  18. Californian thistle rust Californian thistle Phoma