Abstract
The plant hormone salicylic acid (SA) plays a critical role in defense against biotrophic pathogens such as Plasmodiophora brassicae, which is an obligate pathogen of crucifer species and the causal agent of clubroot disease of canola (Brassica napus). P. brassicae encodes a protein, predicted to be secreted, with very limited homology to benzoic acid (BA)/SA-methyltransferase, designated PbBSMT. PbBSMT has a SA- and an indole-3-acetic acid-binding domain, which are also present in Arabidopsis thaliana BSMT1 (AtBSMT1) and, like AtBSMT1, has been shown to methylate BA and SA. In support of the hypothesis that P. brassicae uses PbBSMT to overcome SA-mediated defenses by converting SA into inactive methyl salicylate (MeSA), here, we show that PbBSMT suppresses local defense and provide evidence that PbBSMT is much more effective than AtBSMT1 at suppressing the levels of SA and its associated effects. Basal SA levels in Arabidopsis plants that constitutively overexpress PbBSMT compared with those in Arabidopsis wild-type Col-0 (WT) were reduced approximately 80% versus only a 50% reduction in plants overexpressing AtBSMT1. PbBSMT-overexpressing plants were more susceptible to P. brassicae than WT plants; they also were partially compromised in nonhost resistance to Albugo candida. In contrast, AtBSMT1-overexpressing plants were not more susceptible than WT to either P. brassicae or A. candida. Furthermore, transgenic Arabidopsis and tobacco plants overexpressing PbBSMT exhibited increased susceptibility to virulent Pseudomonas syringae pv. tomato DC3000 (DC3000) and virulent Pseudomonas syringae pv. tabaci, respectively. Gene-mediated resistance to DC3000/AvrRpt2 and tobacco mosaic virus (TMV) was also compromised in Arabidopsis and Nicotiana tabacum 'Xanthi-nc' plants overexpressing PbBSMT, respectively. Transient expression of PbBSMT or AtBSMT1 in lower leaves of N. tabacum Xanthi-nc resulted in systemic acquired resistance (SAR)-like enhanced resistance to TMV in the distal systemic leaves. Chimeric grafting experiments revealed that, similar to SAR, the development of a PbBSMT-mediated SAR-like phenotype was also dependent on the MeSA esterase activity of NtSABP2 in the systemic leaves. Collectively, these results strongly suggest that PbBSMT is a novel effector, which is secreted by P. brassicae into its host plant to deplete pathogen-induced SA accumulation.
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Claims 13
Claim · model-written summary
PbBSMT suppressed local defense.
- Taxon
- Arabidopsis
Arabidopsise1 - Treatment
- PbBSMTe0
- Interactor
- Plasmodiophora brassicae
.jpg?width=60)
Plasmodiophora brassicaet0pathogen - Gene
- PbBSMTe0
- Outcome
- local defensee0
- Direction
- suppressese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“PbBSMT suppresses local defense”
t0“Plasmodiophora brassicae”
e1“Basal SA levels in Arabidopsis plants”
Claim · model-written summary
PbBSMT overexpression reduced Arabidopsis basal SA by approximately 80% versus wild type.
- Taxon
- ArabidopsisArabidopsise0
- Treatment
- constitutively overexpress PbBSMTe0
- Gene
- PbBSMTe0
- Outcome
- Basal SA levelse0
- Direction
- reducede0
- Value
- approximately 80%e0
- Comparator
- Arabidopsis wild-type Col-0 (WT)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Basal SA levels in Arabidopsis plants that constitutively overexpress PbBSMT compared with those in Arabidopsis wild-type Col-0 (WT) were reduced approximately 80%”
Claim · model-written summary
AtBSMT1 overexpression reduced basal SA by 50%.
- Taxon
- ArabidopsisArabidopsise0
- Treatment
- overexpressing AtBSMT1e0
- Gene
- AtBSMT1e0
- Outcome
- SA levelse0
- Direction
- reductione0
- Value
- 50%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Basal SA levels in Arabidopsis plants that constitutively overexpress PbBSMT compared with those in Arabidopsis wild-type Col-0 (WT) were reduced approximately 80% versus only a 50% reduction in plants overexpressing AtBSMT1.”
Claim · model-written summary
PbBSMT overexpression increased Arabidopsis susceptibility to P. brassicae.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- PbBSMT-overexpressinge0
- Interactor
- P. brassicaee0pathogen
- Gene
- PbBSMTe0
- Outcome
- susceptible to P. brassicaee0
- Direction
- moree0
- Comparator
- WT plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PbBSMT-overexpressing plants were more susceptible to P. brassicae than WT plants”
t0“Basal SA levels in Arabidopsis plants”
Claim · model-written summary
PbBSMT overexpression partly compromised nonhost resistance to Albugo candida.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- PbBSMT-overexpressinge0
- Interactor
- Albugo candida
Albugo candidae0pathogen - Outcome
- nonhost resistance to Albugo candidae0
- Direction
- compromisede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PbBSMT-overexpressing plants were more susceptible to P. brassicae than WT plants; they also were partially compromised in nonhost resistance to Albugo candida.”
t0“Basal SA levels in Arabidopsis plants”
Claim · model-written summary
AtBSMT1 overexpression did not increase susceptibility to P. brassicae or A. candida.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- AtBSMT1-overexpressinge0
- Interactor
- P. brassicaee0pathogen
- Second interactor
- A. candidaAlbugo candidae0pathogen
- Outcome
- susceptiblee0
- Direction
- not moree0
- Comparator
- WTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AtBSMT1-overexpressing plants were not more susceptible than WT to either P. brassicae or A. candida.”
t0“Basal SA levels in Arabidopsis plants”
Claim · model-written summary
PbBSMT overexpression increased Arabidopsis susceptibility to Pseudomonas syringae pv. tomato DC3000.
- Taxon
- ArabidopsisArabidopsise0
- Treatment
- overexpressing PbBSMTe0
- Interactor
- Pseudomonas syringae pv. tomato DC3000Pseudomonas syringae pv. tomato str. DC3000e0pathogen
- Outcome
- susceptibilitye0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transgenic Arabidopsis and tobacco plants overexpressing PbBSMT exhibited increased susceptibility to virulent Pseudomonas syringae pv. tomato DC3000 (DC3000) and virulent Pseudomonas syringae pv. tabaci, respectively.”
Claim · model-written summary
PbBSMT overexpression increased tobacco susceptibility to Pseudomonas syringae pv. tabaci.
- Taxon
- tobacco
Nicotiana tabacume0 - Treatment
- overexpressing PbBSMTe0
- Interactor
- Pseudomonas syringae pv. tabaciPseudomonas amygdali pv. tabacie0pathogen
- Outcome
- susceptibilitye0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transgenic Arabidopsis and tobacco plants overexpressing PbBSMT exhibited increased susceptibility to virulent Pseudomonas syringae pv. tomato DC3000 (DC3000) and virulent Pseudomonas syringae pv. tabaci, respectively.”
Claim · model-written summary
PbBSMT compromised Arabidopsis gene-mediated resistance to DC3000/AvrRpt2.
- Taxon
- ArabidopsisArabidopsise0
- Treatment
- overexpressing PbBSMTe0
- Interactor
- DC3000e0pathogen
- Outcome
- Gene-mediated resistance to DC3000/AvrRpt2e0
- Direction
- compromisede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gene-mediated resistance to DC3000/AvrRpt2 and tobacco mosaic virus (TMV) was also compromised in Arabidopsis and Nicotiana tabacum 'Xanthi-nc' plants overexpressing PbBSMT, respectively.”
Claim · model-written summary
PbBSMT compromised tobacco resistance to TMV.
- Taxon
- Nicotiana tabacumNicotiana tabacume0
- Material
- Xanthi-nce0
- Treatment
- overexpressing PbBSMTe0
- Interactor
- tobacco mosaic virus
Tobacco mosaic viruse0pathogen - Outcome
- resistance to DC3000/AvrRpt2 and tobacco mosaic virus (TMV)e0
- Direction
- compromisede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gene-mediated resistance to DC3000/AvrRpt2 and tobacco mosaic virus (TMV) was also compromised in Arabidopsis and Nicotiana tabacum 'Xanthi-nc' plants overexpressing PbBSMT, respectively.”
Claim · model-written summary
Transient PbBSMT expression in lower tobacco leaves enhanced distal resistance to TMV.
- Taxon
- N. tabacumNicotiana tabacume0
- Treatment
- Transient expression of PbBSMTe0
- Interactor
- TMVTobacco mosaic viruse0pathogen
- Outcome
- resistance to TMVe0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transient expression of PbBSMT or AtBSMT1 in lower leaves of N. tabacum Xanthi-nc resulted in systemic acquired resistance (SAR)-like enhanced resistance to TMV in the distal systemic leaves.”
Claim · model-written summary
Transient AtBSMT1 expression in lower tobacco leaves enhanced distal resistance to TMV.
- Taxon
- N. tabacumNicotiana tabacume0
- Treatment
- AtBSMT1e0
- Interactor
- TMVTobacco mosaic viruse0pathogen
- Outcome
- resistance to TMVe0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transient expression of PbBSMT or AtBSMT1 in lower leaves of N. tabacum Xanthi-nc resulted in systemic acquired resistance (SAR)-like enhanced resistance to TMV in the distal systemic leaves.”
Claim · model-written summary
PbBSMT-mediated SAR-like resistance depended on NtSABP2 MeSA esterase activity in systemic leaves.
- Taxon
- N. tabacumNicotiana tabacumt0
- Organ / stage
- systemic leavese0
- Gene
- NtSABP2e0
- Outcome
- PbBSMT-mediated SAR-like phenotypee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the development of a PbBSMT-mediated SAR-like phenotype was also dependent on the MeSA esterase activity of NtSABP2 in the systemic leaves.”
t0“N. tabacum Xanthi-nc”
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See all 55 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.