Regulating
networks and
pathogenicity in
Ustilago maydis
Jörg Kämper
MPI für terrestrische Mikrobiologie
Marburg
Zeae maydis morbus ad ustilaginem vulgo relatus
F.J.Imhof, 1784
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 $!!!
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
Life cycle
of Ustilagomaydis
maydis
Life cycle
of Ustilago
saprophytic
phase
Life cycle
of Ustilagomaydis
maydis
Life cycle
of Ustilago
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
Pant infection with Ustilago maydis
4 days
Pant infection with Ustilago maydis
7 days
Life cycle
of Ustilagomaydis
maydis
Life cycle
of Ustilago
Life cycle
of Ustilagomaydis
maydis
Life cycle
of Ustilago
Life cycle
of Ustilagomaydis
maydis
Life cycle
of Ustilago
Life cycle
of Ustilagomaydis
maydis
Life cycle
of Ustilago
Life cycle
of Ustilagomaydis
maydis
Life cycle
of Ustilago
Life cycle
of Ustilagomaydis
maydis
Life cycle
of Ustilago
Function of the a and b mating type loci
a1b1
a1b1
a2b2
a:
pheromone
signalling
a:
autocrine
response
b:
filamentous
growth
a2b2
a1a2b1b2
plant signals?
b:
pathogenic development
sexual development
Nuclear fusion
Spore formation
Problems in
mating populations
sexual reproduction
50 %
50 %
Problems in
mating populations
sexual reproduction
50 %
50 %
Zur Anzeige w ird der QuickTime™
Dekompressor „TIFF (Unkomprimiert)“
benötigt.
Problems in
mating populations
sexual reproduction
50 %
50 %
Zur Anzeige w ird der QuickTime™
Dekompressor „TIFF (Unkomprimiert)“
benötigt.
Problems in
mating populations
sexual reproduction
- some restrictions
may apply.....
Zur Anzeige w ird der QuickTime™
Dekompressor „TIFF (Unkomprimiert)“
benötigt.
50 %
50 %
Zur Anzeige w ird der QuickTime
Dekompressor „TIFF (Unkomprimier
benötigt.
Problems in
mating populations
a1b1
a2b1
a1b2
a2b2
sexual reproduction
25 %
25 %
Problems in
mating populations
a1b1
a2b1
a1b2
a2b2
sexual reproduction
self/nonself
recognition systems
Fungi:
tetrapolar mating systems
vegetative incompatibility
Plants: pollen rejection
Animals: MHC
25 %
25 %
sexual reproduction
self/nonself
recognition systems
Fungi:
tetrapolar mating systems
vegetative incompatibility
Plants: pollen rejection
Animals: MHC
Podospora anserina
Problems in
mating populations
sexual reproduction
self/nonself
recognition systems
Fungi:
tetrapolar mating systems
vegetative incompatibility
Plants: pollen rejection
Animals: MHC
Problems in
mating populations
sexual reproduction
self/nonself
recognition systems
Fungi:
tetrapolar mating systems
vegetative incompatibility
Plants: pollen rejection
Animals: MHC
< 50 %
< 50 %
Two component self/nonself discrimination systems
self
non-self
Two component self/nonself discrimination systems
Mutation
Recognition as: non-self
Consequences:
plants: self-pollination
fungi: cell death
self-fertility
Two component self/nonself discrimination systems
Mutation
Recognition as: non-self
?
The b mating type encodes the central regulator for
pathogenic development
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
- sequencing: 18 strains from ATCC
- screening of > 200 field isolates for novel RFLP
- identification of one novel specificity
342
b4b
b2
b10
b2
b5
b8
b16
b8
bW3
bW4
bE3
bE4
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
PCR-knockout
PCR-knockout
a
resistance cassette
a
SfiI: ggccnnnn nggcc
PCR-knockout
PCR-knockout
rb2.1n
rb2.2n
283 Eco RI •
597 Pst I •
lb
1296 Sfi I •
1584 Pst I •
1594 Not I •
pCR-b-k o-ne u(+)
hph
• Nco I 5785
7837 bp
2271 Nco I •
2290 Pst I •
2380 Eco RI •
• Pst I 5402
2625 Nco I •
3180 Sfi I •
• Not I 4256
• Pst I 4235
• Eco RI 4230
• Sna BI 4121
rb
3767 Eco RI •