J

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Regulating networks and pathogenicity in Ustilago
maydis
Jörg Kämper MPI für terrestrische
Mikrobiologie Marburg
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Economical losses by smut fungi - high annual
losses, local losses sometimes more than
25 Ustilago hordei 0.7 - 1,4 loss/year
(Canada) appr. 17.6 Mio US /year Ustilago
maydis usually less than 2, but up to 70 2
in USA equals about 380 Mio US !!!
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Economical losses by smut fungi - high annual
losses, local losses sometimes more than
25 Ustilago hordei 0.7 - 1,4 loss/year
(Canada) appr. 17.6 Mio US /year Ustilago
maydis usually less than 2, but up to 70 2
in USA equals about 380 Mio US !!!
Related to rust fungi (obligat biotroph)

• extremly high annual losses
• Epidemics

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Life cycle of Ustilago maydis
Life cycle of Ustilago maydis
saprophytic phase
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Life cycle of Ustilago maydis
Life cycle of Ustilago maydis
saprophytic phase
Saprophytic phase Simple cultivation under lab
conditions Various molecular techniques - gene
replacement - ARS plasmids - regulatable
promoters - GFP reporter - REMI - transposon
tagging - fast infection model
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Pant infection with Ustilago maydis
4 days
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Pant infection with Ustilago maydis
7 days
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Life cycle of Ustilago maydis
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Life cycle of Ustilago maydis
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Life cycle of Ustilago maydis
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Life cycle of Ustilago maydis
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Life cycle of Ustilago maydis
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Life cycle of Ustilago maydis
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Function of the a and b mating type loci
a1b1
a2b2
a1b1
a2b2
a1a2b1b2
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Problems in mating populations
sexual reproduction
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50
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Problems in mating populations
sexual reproduction
50
50
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Problems in mating populations
sexual reproduction
50
50
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Problems in mating populations

• sexual reproduction
• some restrictions
• may apply.....

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50
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Problems in mating populations
a1b1
a2b1
sexual reproduction
a1b2
a2b2
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25
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Problems in mating populations
a1b1
a2b1
sexual reproduction self/nonself recognition
systems Fungi tetrapolar mating
systems vegetative incompatibility Plants pollen
rejection Animals MHC
a1b2
a2b2
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25
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sexual reproduction self/nonself recognition
systems Fungi tetrapolar mating
systems vegetative incompatibility Plants pollen
rejection Animals MHC
Podospora anserina
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Problems in mating populations
sexual reproduction self/nonself recognition
systems Fungi tetrapolar mating
systems vegetative incompatibility Plants pollen
rejection Animals MHC
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Problems in mating populations
sexual reproduction self/nonself recognition
systems Fungi tetrapolar mating
systems vegetative incompatibility Plants pollen
rejection Animals MHC
lt 50
lt 50
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Two component self/nonself discrimination systems
self
non-self
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Two component self/nonself discrimination systems
Mutation
Consequences plants self-pollination fungi
cell death self-fertility
Recognition as non-self
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Two component self/nonself discrimination systems
Mutation
?
Recognition as non-self
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The b mating type encodes the central regulator
for pathogenic development
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The b mating type encodes the central regulator
for pathogenic development

• specificity is determined within the variable
  domains
• variable domains are sufficient for dimerization
• mutations within the variable domain alter
  dimerization AND specificity

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- sequencing 18 strains from ATCC - screening
of gt 200 field isolates for novel RFLP -
identification of one novel specificity
342
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b4b
b2
b10
b2
b2
b10
b2
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b5
b8
b16
b8
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Genetic manipulations gene replacement
resistence gene
PCR-based system homologous recombination up to
100
Schreier, P und Kämper, J European Patent 1 279
741 A1
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PCR-knockout
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PCR-knockout
a
resistance cassette
a
SfiI ggccnnnn nggcc
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PCR-knockout
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PCR-knockout
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