Ustilago maydis

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Ustilago maydis Common smut disease of maize
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a1b1
Ustilago maydis is a dimorphic fungus
Mating
a2b2
Infection
Vegetative Growth
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Diseased
Healthy
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Does pollination protect maize ovaries from
smut infection?

• Indications from greenhouse experiments
• Support from field experiments of du Toit and
  Pataky
• Interest in smut production as well as prevention

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Controlled pollination experiment

• Field study
• Susceptible variety (Golden Cross Bantam)
• Four treatments (30 ears each)
• pollination only
• inoculation only
• pollination, then inoculation four days later
• inoculation, then pollination four days later
• Ears treated sequentially over 3 weeks

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Cut silk method of pollination
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How are the ovaries protected by pollination?
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Normal infection structures are found on
pollinated silks
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Hyphae can invade pollinated silks
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Hyphae
Pollen tube
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abscission zone
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ovary
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• Gametophyte (pollen) characters may be important
  in resistance to corn smut.
• Is there any cellular resistance to smut
  infection?
• Next step is to examine resistant varieties

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Acknowledgements

• Howard Hughes Medical Institute Summer Research
  Program
• NSF grants MCB9807807, DBI9724401
• SJU Grounds Crew

Kelly Cordisco
Meghan Carfioli
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Current (almost) Ustilago group