Abstract
Recent research has implicated nitric oxide (NO) in the induction of the hypersensitive response (HR) during plant-pathogen interactions. Here we demonstrate that Arabidopsis suspension cultures generate elevated levels of NO in response to challenge by avirulent bacteria, and, using NO donors, show that these elevated levels of NO are sufficient to induce cell death in Arabidopsis cells independently of reactive oxygen species (ROS). We also provide evidence that NO-induced cell death is a form of programmed cell death (PCD), requiring gene expression, and has a number of characteristics of PCD of mammalian cells: NO induced chromatin condensation and caspase-like activity in Arabidopsis cells, while the caspase-1 inhibitor, Ac-YVAD-CMK, blocked NO-induced cell death. A well-established second messenger mediating NO responses in mammalian cells is cGMP, produced by the enzyme guanylate cyclase. A specific inhibitor of guanylate cyclase blocked NO-induced cell death in Arabidopsis cells, and this inhibition was reversed by the cell-permeable cGMP analogue, 8Br-cGMP, although 8Br-cGMP alone did not induce cell death or potentiate NO-induced cell death. This suggests that cGMP synthesis is required but not sufficient for NO-induced cell death in Arabidopsis. In-gel protein kinase assays showed that NO activates a potential mitogen-activated protein kinase (MAPK), although a specific inhibitor of mammalian MAPK activation, PD98059, which blocked H2O2-induced cell death, did not inhibit the effects of NO.
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Claims 14
Claim · model-written summary
Avirulent bacterial challenge elevated nitric oxide in Arabidopsis suspension cultures.
- Taxon
- Arabidopsis
Arabidopsise0 - Treatment
- challenge by avirulent bacteriae0
- Interactor
- avirulent bacteriae0pathogen
- Outcome
- levels of NOe0
- Direction
- elevatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis suspension cultures generate elevated levels of NO in response to challenge by avirulent bacteria”
Claim · model-written summary
Nitric oxide donors induced Arabidopsis cell death independently of reactive oxygen species.
- Taxon
- ArabidopsisArabidopsise0
- Treatment
- NO donorse0
- Outcome
- cell deathe0
- Qualifier
- independently of reactive oxygen species (ROS)e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“using NO donors, show that these elevated levels of NO are sufficient to induce cell death in Arabidopsis cells independently of reactive oxygen species (ROS)”
Claim · model-written summary
Nitric-oxide-induced cell death was characterized as programmed cell death requiring gene expression.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- NO-induced cell deathe0
- Qualifier
- requiring gene expressione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NO-induced cell death is a form of programmed cell death (PCD), requiring gene expression”
t0“Arabidopsis”
Claim · model-written summary
Nitric oxide induced chromatin condensation in Arabidopsis cells.
- Taxon
- ArabidopsisArabidopsise0
- Treatment
- NOe0
- Outcome
- chromatin condensatione0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NO induced chromatin condensation and caspase-like activity in Arabidopsis cells”
Claim · model-written summary
Nitric oxide induced caspase-like activity in Arabidopsis cells.
- Taxon
- ArabidopsisArabidopsise0
- Treatment
- NOe0
- Outcome
- caspase-like activitye0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NO induced chromatin condensation and caspase-like activity in Arabidopsis cells”
Claim · model-written summary
The caspase-1 inhibitor Ac-YVAD-CMK blocked nitric-oxide-induced cell death.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Ac-YVAD-CMKe0
- Outcome
- NO-induced cell deathe0
- Direction
- blockede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the caspase-1 inhibitor, Ac-YVAD-CMK, blocked NO-induced cell death”
t0“Arabidopsis”
Claim · model-written summary
A guanylate cyclase inhibitor blocked nitric-oxide-induced cell death.
- Taxon
- ArabidopsisArabidopsise0
- Treatment
- inhibitor of guanylate cyclasee0
- Outcome
- NO-induced cell deathe0
- Direction
- blockede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A specific inhibitor of guanylate cyclase blocked NO-induced cell death in Arabidopsis cells”
Claim · model-written summary
The cGMP analogue 8Br-cGMP reversed guanylate cyclase inhibitor blockade.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- 8Br-cGMPe0
- Outcome
- inhibitione0
- Direction
- reversede0
- Comparator
- this inhibitione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this inhibition was reversed by the cell-permeable cGMP analogue, 8Br-cGMP”
t0“Arabidopsis”
Claim · model-written summary
8Br-cGMP alone did not induce cell death.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- 8Br-cGMP alonee0
- Outcome
- cell deathe0
- Direction
- did not inducee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“8Br-cGMP alone did not induce cell death”
t0“Arabidopsis”
Claim · model-written summary
8Br-cGMP did not potentiate nitric-oxide-induced cell death.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- 8Br-cGMPe0
- Outcome
- NO-induced cell deathe0
- Direction
- did note0
- Qualifier
- potentiatee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“8Br-cGMP alone did not induce cell death or potentiate NO-induced cell death”
t0“Arabidopsis”
Claim · model-written summary
The authors infer cGMP synthesis is required but insufficient for nitric-oxide-induced cell death.
- Taxon
- ArabidopsisArabidopsise0
- Compound
- cGMPe0
- Outcome
- NO-induced cell deathe0
- Qualifier
- required but not sufficiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cGMP synthesis is required but not sufficient for NO-induced cell death in Arabidopsis”
Claim · model-written summary
Nitric oxide activated a potential MAPK in protein kinase assays.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- NOe0
- Gene
- mitogen-activated protein kinase (MAPK)e0
- Outcome
- potential mitogen-activated protein kinase (MAPK)e0
- Direction
- activatese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NO activates a potential mitogen-activated protein kinase (MAPK)”
t0“Arabidopsis”
Claim · model-written summary
PD98059 blocked H2O2-induced cell death.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- PD98059e0
- Outcome
- H2O2-induced cell deathe0
- Direction
- blockede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PD98059, which blocked H2O2-induced cell death”
t0“Arabidopsis”
Claim · model-written summary
PD98059 did not inhibit nitric oxide effects.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- PD98059e0
- Outcome
- effects of NOe0
- Direction
- did not inhibite0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PD98059, which blocked H2O2-induced cell death, did not inhibit the effects of NO”
t0“Arabidopsis”
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See all 7 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.