Title: Recent advances in
1Recent advances in understanding gene for
gene interactions
2 Avirulence Gene Function what is currently
known
Avr Protein
Pathogen
Homology with and/or possible virulence function
Location in the plant cell
Common domain for avirulence and virulence
function
Location of the matching R gene
AvrPphC
Pseudomonas syringae pv. phaseolicola
Interferes with the plant defense response
NK
NK
NK
AvrPphF
Pseudomonas syringae pv. phaseolicola
Interferes with the plant defense response
NK
NK
NK
AvrRpt2
Pseudomonas syringae pv. tomato
Interferes with the plant defense response
NK
NK
NK
AvrRpm1
Pseudomonas syringae pv. maculicola
Enhances growth
Plasma membrane
NK
Plasma membrane
AvrPto
Pseudomonas syringae pv. tomato
Enhances growth Degradation of resistance gene
Plasma membrane
No
NK
AvrBst
Xanthomonas campestris pv. campestris
Ubiquitin-like protease
NK
Yes
NK
AvrXa7
Xanthomonas oryzae pv. oryzae
Transcriptional activation domain required for
virulence
Nucleus
Yes
NK
AvrBs2
Xanthomonas campestris pv. vesicatoria
Agrocinopine synthase (from Agrobacterium
tumefaciens)
NK
Recognition region localized in the portion with
highest homology to synthase
NK
AvrBs3
Xanthomonas campestris pv. glycinea
Transcriptional activation domain required for
virulence
Nucleus
Yes
NK
PthA
Xanthomonas citri
Transcriptional activation domain required for
virulence/causes cell hyperplasia 53
Nucleus
NK
NK
Avr9
Cladosporium fulvum
NK
Exoplasmic
NK
External plasma membrane
3Avirulence genes promote virulence
Chen et al., (2000) The Pseudomonas syringae
avrRpt2 Gene Product Promotes Pathogen Virulence
from Inside Plant Cells. Molecular Plant-Microbe
Interactions Vol. 13 13121321
Disease symptoms and growth of Pseudomonas
syringae pv. tomato strain DC3000 (PstDC3000) on
Arabidopsis thaliana leaf tissue. A,
Diseasesymptoms caused by PstDC3000 on A.
thaliana No-0 rps2 (top) and Col-0 rps2 (bottom)
plants. Leaves are shown 4 days after inoculation
with PstDC3000 (left) and PstDC3000(avrRpt2)
(right). Plants were inoculated by dipping them
into bacterial suspensions (3 to 5 10 8 CFU/cm
2 ) containing the surfactant Silwet L-77. B,
Growth of PstDC3000 and PstDC3000(avrRpt2) in
leaf tissue of Col-0 rps2, No-0 rps2, and No-0
RPS2 plants.. In B, A. thaliana plants were
inoculated by vacuum infiltration with the
indicated PstDC3000 strains at an initial density
of 1 10 5 CFU/cm 2 . The concentration of
bacteria in the plant leaves was assayed after 0,
2, and 4 days. Datapoints represent means of
three independent determinations standard error
of the mean. Experiments presented in A, B, were
carried out a minimum of three times with similar
results
4Virulence genes suppress avr/R gene interactions
Chen et al., (2000) The Pseudomonas syringae
avrRpt2 Gene Product Promotes Pathogen Virulence
from Inside Plant Cells. Molecular Plant-Microbe
Interactions Vol. 13 13121321
5RPM1MYC is a peripheral PM protein.
C-Myc epitope has been artificially added to
RPM1
Anti-myc antibody can be used to detect
myc- labelled RPM1
Plasma Membrane
Cytoplasm and ER
Boyes et al., (1998) The Arabidopsis thaliana
RPM1 disease resistance gene product is a
peripheral plasma membrane protein that is
degraded coincident with the hypersensitive
response. 95, PNAS USA 15849-15854
6AvrRpm1 and avrB localise to the plant cell
membrane. Protoplasts from rpm1 plants were
transformed with plasmid that express either
avr-GFP or avrG2A-GFP constructs. Control
transformations were with GFP alone.
avrRpm1 N-terminal fatty acylation sequence
avrRpm1 MGCVSSTSR Soc3a MGCSVSKKK Ca sensor
G2A glycine change to alanine Loss in
avirulence
7RPM1MYC is degraded after inoculation with
avirulent P. syringae isolates, which trigger
LZ-NBS-LRR resistance genes
Hours post inoculation
Boyes et al., (1998) The Arabidopsis thaliana
RPM1 disease resistance gene product is a
peripheral plasma membrane protein that is
degraded coincident with the hypersensitive
response. 95, PNAS USA 15849-15854
8AvrXa7 a nuclear targeted protein
PX086mx53 NLS- version
Resistant
Susceptible
NORMAL
avrXa7 over express
avrXa7 express
avrXa7 NLS-
NORMAL
avrXa7 over express
avrXa7 express
avrXa7 NLS-
Fig. 1. AvrXa7 is a DNA-binding protein.
Double-stranded oligonucleotides were end labeled
with 32P, mixed with AvrXa7 or GST (glutathione
S-transferase), and subjected to polyacrylamide
electrophoresis. Arrow indicates position of
well.
Yang et al., (2000) The virulence factor AvrXa7
of Xanthomonas oryzae pv. oryzae is a type III
secretion pathway-dependent nuclear-localized
double-stranded DNA-binding protein.Proc Natl
Acad Sci U S A 159807
9Guard Hypotheses