Abstract
The Gram-negative bacterium Xanthomonas euvesicatoria (Xe) is the causal agent of bacterial spot disease of pepper and tomato. Xe delivers effector proteins into host cells through the type III secretion system to promote disease. Here, we show that the Xe effector XopAU, which is conserved in numerous Xanthomonas species, is a catalytically active protein kinase and contributes to the development of disease symptoms in pepper plants. Agrobacterium-mediated expression of XopAU in host and non-host plants activated typical defense responses, including MAP kinase phosphorylation, accumulation of pathogenesis-related (PR) proteins and elicitation of cell death, that were dependent on the kinase activity of the effector. XopAU-mediated cell death was not dependent on early signaling components of effector-triggered immunity and was also observed when the effector was delivered into pepper leaves by Xanthomonas campestris pv. campestris, but not by Xe. Protein-protein interaction studies in yeast and in planta revealed that XopAU physically interacts with components of plant immunity-associated MAP kinase cascades. Remarkably, XopAU directly phosphorylated MKK2 in vitro and enhanced its phosphorylation at multiple sites in planta. Consistent with the notion that MKK2 is a target of XopAU, silencing of the MKK2 homolog or overexpression of the catalytically inactive mutant MKK2K99R in N. benthamiana plants reduced XopAU-mediated cell death and MAPK phosphorylation. Furthermore, yeast co-expressing XopAU and MKK2 displayed reduced growth and this phenotype was dependent on the kinase activity of both proteins. Together, our results support the conclusion that XopAU contributes to Xe disease symptoms in pepper plants and manipulates host MAPK signaling through phosphorylation and activation of MKK2.
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Claims 14
Claim · model-written summary
XopAU is a catalytically active protein kinase.
- Taxon
- pepper plantse1
- Interactor
- Xanthomonas species
_-_Howard_F._Schwartz%2C_Colorado_State_University.jpg?width=60)
Xanthomonase0pathogen - Gene
- XopAUe0
- Outcome
- catalytically active protein kinasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_-_Howard_F._Schwartz%2C_Colorado_State_University.jpg?width=500)
Verbatim
e0“the Xe effector XopAU, which is conserved in numerous Xanthomonas species, is a catalytically active protein kinase”
t0“plant MAP kinase signaling”
e1“contributes to the development of disease symptoms in pepper plants”
Claim · model-written summary
XopAU contributes to disease symptoms in pepper.
Verbatim
e0“contributes to the development of disease symptoms in pepper plants”
Claim · model-written summary
XopAU expression activated MAP kinase phosphorylation in host and non-host plants.
- Taxon
- plantsViridiplantaee0
- Treatment
- Agrobacterium-mediated expression of XopAUe0
- Gene
- XopAUe0
- Outcome
- MAP kinase phosphorylatione0
- Direction
- activatede0
Not reportedComparator
Verbatim
e0“Agrobacterium-mediated expression of XopAU in host and non-host plants activated typical defense responses, including MAP kinase phosphorylation”
Claim · model-written summary
XopAU expression induced accumulation of PR proteins.
- Taxon
- plantsViridiplantaee0
- Treatment
- Agrobacterium-mediated expression of XopAUe0
- Gene
- XopAUe0
- Outcome
- accumulation of pathogenesis-related (PR) proteinse0
- Direction
- accumulatione0
Not reportedComparator
Verbatim
e0“Agrobacterium-mediated expression of XopAU in host and non-host plants activated typical defense responses, including MAP kinase phosphorylation, accumulation of pathogenesis-related (PR) proteins and elicitation of cell death”
Claim · model-written summary
XopAU expression elicited cell death dependent on kinase activity.
Not reportedComparatorDirection
Verbatim
e0“elicitation of cell death, that were dependent on the kinase activity of the effector”
t0“plant MAP kinase signaling”
e1“contributes to the development of disease symptoms in pepper plants”
Claim · model-written summary
XopAU cell death was independent of early effector-triggered immunity signaling components.
Verbatim
e0“XopAU-mediated cell death was not dependent on early signaling components of effector-triggered immunity”
t0“plant MAP kinase signaling”
e1“contributes to the development of disease symptoms in pepper plants”
Claim · model-written summary
XopAU delivered by Xanthomonas campestris pv. campestris induced cell death in pepper leaves.
- Taxon
- peppere0
- Treatment
- delivered into pepper leaves by Xanthomonas campestris pv. campestrise0
- Interactor
- Xanthomonas campestris pv. campestris
Xanthomonas campestris pv. campestrise0pathogen - Outcome
- cell deathe0
- Comparator
- Xee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“XopAU-mediated cell death was not dependent on early signaling components of effector-triggered immunity and was also observed when the effector was delivered into pepper leaves by Xanthomonas campestris pv. campestris, but not by Xe”
Claim · model-written summary
XopAU interacted physically with components of plant immunity MAP kinase cascades.
Verbatim
e0“XopAU physically interacts with components of plant immunity-associated MAP kinase cascades”
Claim · model-written summary
XopAU phosphorylated MKK2 in vitro.
Verbatim
e0“XopAU directly phosphorylated MKK2 in vitro”
t0“plant MAP kinase signaling”
e1“contributes to the development of disease symptoms in pepper plants”
Claim · model-written summary
XopAU enhanced MKK2 phosphorylation at multiple sites in planta.
Verbatim
e0“enhanced its phosphorylation at multiple sites in planta”
t0“plant MAP kinase signaling”
e1“contributes to the development of disease symptoms in pepper plants”
e2“XopAU directly phosphorylated MKK2 in vitro”
Claim · model-written summary
Silencing the MKK2 homolog reduced XopAU cell death and MAPK phosphorylation in N. benthamiana.
- Taxon
- N. benthamianae0
- Treatment
- silencing of the MKK2 homologe0
- Gene
- MKK2 homologe0
- Outcome
- XopAU-mediated cell death and MAPK phosphorylatione0
- Direction
- reducede0
Not reportedComparator
Verbatim
e0“silencing of the MKK2 homolog or overexpression of the catalytically inactive mutant MKK2K99R in N. benthamiana plants reduced XopAU-mediated cell death and MAPK phosphorylation”
Claim · model-written summary
MKK2K99R overexpression reduced XopAU cell death and MAPK phosphorylation in N. benthamiana.
- Taxon
- N. benthamianae0
- Treatment
- overexpression of the catalytically inactive mutant MKK2K99Re0
- Gene
- MKK2K99Re0
- Outcome
- XopAU-mediated cell death and MAPK phosphorylatione0
- Direction
- reducede0
Not reportedComparator
Verbatim
e0“overexpression of the catalytically inactive mutant MKK2K99R in N. benthamiana plants reduced XopAU-mediated cell death and MAPK phosphorylation”
Claim · model-written summary
XopAU and MKK2 coexpression reduced yeast growth in a kinase dependent manner.
Verbatim
e0“yeast co-expressing XopAU and MKK2 displayed reduced growth and this phenotype was dependent on the kinase activity of both proteins”
t0“plant MAP kinase signaling”
e1“contributes to the development of disease symptoms in pepper plants”
Claim · model-written summary
The authors conclude that XopAU manipulates host MAPK signaling by phosphorylation and activation of MKK2.
Verbatim
e0“manipulates host MAPK signaling through phosphorylation and activation of MKK2”
t0“plant MAP kinase signaling”
e1“contributes to the development of disease symptoms in pepper plants”
The same questions in other papers
transgenic · molecular: expression · Viridiplantae (plants)Positive and negative results
2 in the opposite direction · 1 reporting no difference from an alternative
- negative
- no effect
- no effect
loss of function · molecular: expression · Nicotiana benthamianaPositive and negative results
18 papers in the same direction as this paper · 24 in the opposite direction
- negative
- negative
- negative
39 papers more in this group
See all 43 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.