6. Confers resistance to several races of
Puccinia graminis f. sp. tritici
Brueggeman et al., PNAS, 2002
Map based cloning from
cultivar “Morex”
pK1 pK2
1 837
8. Expressed constitutively in all organs
Expressed at higher levels in the leaf
epidermis!!!
Does not significantly modulate in response to
pathogen attack
Rostoks et al., PMPP, 2004
9. Mostly cytoplasmic, with a minor membrane association
Is a functionally active S/T kinase
pK1 pK2
1 837
catalytically
Inactive
catalytically
active
Both the domains required for disease resistance!!!!
Nirmala et al., PNAS, 2006
10. RPG1 Phosphorylation
5 min after spore
landing
Degradation
20-24hai
Highly race specific and required for
resistance!!!
Nirmala et al., 2007, PNAS Nirmala et al., 2010, MPMI
Elicitor is probably located on the
surface of the spore!!!
11. Background on stem rust and Rpg1
AvrRpg1 genes/proteins
RGD peptides and rust control
Summary/Speculations
12. Adhesion pad
Nirmala et al., 2011, PNAS
RGD peptide treated spores Untreated Spores
RGD: Arginine-Glycine-Aspartic acid
15. P
U
0.25hai20hai
24
hai48
hai
PS
PT
RPG1
Morex
Steptoe
ASM170
Puccinia graminis f. sp. tritici
urediniospore extract binding to
and eluted from the RGD affinity
column induced RPG1
phosphorylation and degradation
in barley cv. Morex
Puccinia graminis f. sp. tritici
urediniospore extract binding to
and eluted from the RGD affinity
column induced HR in barley
harboring a functional Rpg1 gene
RGD: Arginine, Glycine
and Aspartic acidP: Positive control
U: Uninoculated control
PS: Phosphoserine antibody
PT: Phosphothreonine antibody
16. 3
Fibronectin
Type III
domain
BRCA1 C-terminal
Domain
5
Cell surface
recognition and
attachment
Phosphopeptide binding,
Phosphorylation and
protein-protein interaction
1bp
2918 bp
Has no known recognition motifs or an obvious signal peptide!!!
17. VPS9 domain CUE
domain
5 3
Vacuolar
transport
Ubiquitination
Has no known recognition motifs or an obvious signal peptide!!!
21. The RPG1 pK1 and pK2 mutants failed to interact with the RGD-binding
and the VPS9 proteins.
A
B C
Positive control
SOS-VPS9+Myr-RPG1
SOS-VPS9+Myr-pK1-RPG1
SOS-VPS9+pMyr-pK2-RPG1
SOS-RGD+Myr-RPG1
SOS-RGD+Myr-pK1-RPG1
SOS-RGD+Myr-pK2-RPG1
Negative control
SD/GLU-UL SD/GAL-ULSD/GLU-UL
25 C
0
37 C
0
37 C
0
91.8 kDa
196.2 kDa
4 5 6
206.9 kDa
91.8 kDa
1 2 3
Nirmala et al., 2011, PNAS
27. Race
Muta/on
RPG1
Phosphoryla/on
ac/vity
MCCF
P565S
Looses
ac/vity
MCCF
S52P
Looses
ac/vity
MCCF
D481E
Looses
ac/vity
MCCF
E665D
Looses
ac/vity
MCCF
N725I
Looses
ac/vity
MCCF
Q787H
Looses
ac/vity
QCCJ
P52S
Does
not
regain
ac/vity
QCCJ
E481D
Does
not
regain
ac/vity
92MN90
I725N
Does
not
regain
ac/vity
92MN90
D665E
Does
not
regain
ac/vity
Ug99
H787Q
Does
not
regain
ac/vity
QCCJ
S565P
Does
not
regain
ac/vity
92MN90
S565P
Does
not
regain
ac/vity
Ug99
S565P
Does
not
regain
ac/vity
QCCJ
P52S,
E481D
Does
not
regain
ac/vity
92MN90
I725N,
D665E
Does
not
regain
ac/vity
Ug99
H787Q,
S565P
Regains
ac/vity
QCCJ
P52S,
E481D,
S565P
Regains
ac/vity
92MN90
I725N,
D665E,
S565P
Regains
ac/vity
28. Race
Muta/on
RPG1
degrada/on
MCCF
A527V
Looses
ability
to
degrade
RPG1
MCCF
S518N
Looses
ability
to
degrade
RPG1
QCCJ
V527A
Regains
Ability
to
degrade
RPG1
Ug99
V527A
Regains
ability
to
degrade
RPG1
92MN90-‐2
V527A
Regains
ability
to
degrade
RPG1
92MN90-‐1
V527A
Does
not
regain
ability
to
degrade
RPG1
92MN90-‐1
N518S
Does
not
regain
ability
to
degrade
RPG1
92MN90-‐1
V527A/N518S
Regains
ability
to
degrade
RPG1
RPG1 phosphorylation was induced with MCCF-RGD binding protein
29. Background on stem rust and Rpg1
AvrRpg1 genes
RGD peptides and rust control
Summary/Speculations
33. Background on stem rust and Rpg1
AvrRpg1 genes
RGD peptides and rust control
Summary/Speculations
34. Phosphorylation of RPG1 acts as the initial signal for
activating the defense response
Two novel effectors work together in activating RPG1
They are present on the surface of the spores and the
recognition probably occurs at the surface of the plant
cells
Mutational analysis reveals that single amino acid
substitutions alters effector recognition and activation
Stabilized RGD peptides can be exploited to control
rust
35. 1) RGD binding protein interacts with RPG1 and other
proteins at the cell membrane and RPG1 may act as a
receptor
2) If so RPG1 might be a integrin like molecule mediating
inside-out signaling!
3) RPG1 does not have a RGD motif in the right
orientation-therefore might need another protein/integrin
which acts as a receptor, which might phosphorylate
RPG1 and initiate defense signaling
36. 4) Why are these avirulent forms retained if it is so
easy to change to virulence by mutation?
a) Do they serve some other function?
5) Exploit the stabilized RGD peptides to control
the rusts
37. Research was supported by National Research Initiative of the United
States Department of Agriculture Co-operative State Research,
Education, and Extension Service Grant No. 2007-35301-18205 and
National Institute of Food and Agriculture Grant No. 2010-65108-20568.
Durable rust resistance in wheat
Dr. Andris Kleinhofs
Dr. Diter Von Wettstein
Dr. Scot Hulbert
Dr. Xianming Chen
Dr. Brian Steffenson
Dr. Pablo Olivera
Dr. Mathew Rouse
Dr. Les Szabo
