Abstract
Recognition of a pathogen avirulence (AVR) effector protein by a cognate plant resistance (R) protein triggers a set of immune responses that render the plant resistant. Pathogens can escape this so-called Effector-Triggered Immunity (ETI) by different mechanisms including the deletion or loss-of-function mutation of the AVR gene, the incorporation of point mutations that allow recognition to be evaded while maintaining virulence function, and the acquisition of new effectors that suppress AVR recognition. The Dothideomycete Leptosphaeria maculans, causal agent of oilseed rape stem canker, is one of the few fungal pathogens where suppression of ETI by an AVR effector has been demonstrated. Indeed, AvrLm4-7 suppresses Rlm3- and Rlm9-mediated resistance triggered by AvrLm3 and AvrLm5-9, respectively. The presence of AvrLm4-7 does not impede AvrLm3 and AvrLm5-9 expression, and the three AVR proteins do not appear to physically interact. To decipher the epistatic interaction between these L. maculans AVR effectors, we determined the crystal structure of AvrLm5-9 and obtained a 3D model of AvrLm3, based on the crystal structure of Ecp11-1, a homologous AVR effector candidate from Fulvia fulva. Despite a lack of sequence similarity, AvrLm5-9 and AvrLm3 are structural analogues of AvrLm4-7 (structure previously characterized). Structure-informed sequence database searches identified a larger number of putative structural analogues among L. maculans effector candidates, including the AVR effector AvrLmS-Lep2, all produced during the early stages of oilseed rape infection, as well as among effector candidates from other phytopathogenic fungi. These structural analogues are named LARS (for Leptosphaeria AviRulence and Suppressing) effectors. Remarkably, transformants of L. maculans expressing one of these structural analogues, Ecp11-1, triggered oilseed rape immunity in several genotypes carrying Rlm3. Furthermore, this resistance could be suppressed by AvrLm4-7. These results suggest that Ecp11-1 shares a common activity with AvrLm3 within the host plant which is detected by Rlm3, or that the Ecp11-1 structure is sufficiently close to that of AvrLm3 to be recognized by Rlm3.
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Claims 9
Claim · model-written summary
AvrLm4-7 suppresses Rlm3 mediated resistance triggered by AvrLm3.
- Taxon
- oilseed rape
_Brassica_napus_-_Habit.jpg?width=60)
Brassica napust0 - Interactor
- Leptosphaeria maculans
Plenodomus lingame1pathogene0 - Gene
- AvrLm4-7e0
- Outcome
- Rlm3- and Rlm9-mediated resistancee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Brassica_napus_-_Habit.jpg?width=500)
Verbatim
e0“AvrLm4-7 suppresses Rlm3- and Rlm9-mediated resistance triggered by AvrLm3 and AvrLm5-9, respectively.”
t0“oilseed rape stem canker”
e1“Leptosphaeria maculans”
Claim · model-written summary
AvrLm4-7 suppresses Rlm9 mediated resistance triggered by AvrLm5-9.
- Taxon
- oilseed rapeBrassica napust0
- Interactor
- Leptosphaeria maculansPlenodomus lingame1pathogene0
- Gene
- AvrLm5-9e0
- Outcome
- Rlm3- and Rlm9-mediated resistancee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AvrLm4-7 suppresses Rlm3- and Rlm9-mediated resistance triggered by AvrLm3 and AvrLm5-9, respectively.”
t0“oilseed rape stem canker”
e1“Leptosphaeria maculans”
Claim · model-written summary
AvrLm4-7 did not impede AvrLm3 or AvrLm5-9 expression.
- Taxon
- oilseed rapeBrassica napust0
- Interactor
- Leptosphaeria maculansPlenodomus lingame1pathogene0
- Gene
- AvrLm4-7e0
- Outcome
- AvrLm3 and AvrLm5-9 expressione0
- Direction
- does not impedee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The presence of AvrLm4-7 does not impede AvrLm3 and AvrLm5-9 expression”
t0“oilseed rape stem canker”
e1“Leptosphaeria maculans”
Claim · model-written summary
The three AVR proteins did not appear to physically interact.
- Taxon
- oilseed rapeBrassica napust0
- Interactor
- Leptosphaeria maculansPlenodomus lingame1pathogene0
- Outcome
- the three AVR proteins do not appear to physically interacte0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the three AVR proteins do not appear to physically interact”
t0“oilseed rape stem canker”
e1“Leptosphaeria maculans”
Claim · model-written summary
AvrLm5-9 and AvrLm3 were structural analogues of AvrLm4-7 despite sequence dissimilarity.
- Taxon
- oilseed rapeBrassica napust0
- Interactor
- Leptosphaeria maculansPlenodomus lingame1pathogene0
- Gene
- AvrLm5-9 and AvrLm3e0
- Outcome
- structural analogues of AvrLm4-7e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Despite a lack of sequence similarity, AvrLm5-9 and AvrLm3 are structural analogues of AvrLm4-7”
t0“oilseed rape stem canker”
e1“Leptosphaeria maculans”
Claim · model-written summary
Sequence searches identified further structural analogues among L. maculans effectors including AvrLmS-Lep2.
- Taxon
- oilseed rapeBrassica napust0
- Interactor
- L. maculansPlenodomus lingame0pathogen
- Gene
- AvrLmS-Lep2e0
- Outcome
- putative structural analogues among L. maculans effector candidatese0
- Value
- a larger numbere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Structure-informed sequence database searches identified a larger number of putative structural analogues among L. maculans effector candidates, including the AVR effector AvrLmS-Lep2”
t0“oilseed rape stem canker”
Claim · model-written summary
The searches also identified analogous effectors in other phytopathogenic fungi.
- Taxon
- oilseed rapeBrassica napust0
- Interactor
- other phytopathogenic fungie0pathogen
- Outcome
- effector candidates from other phytopathogenic fungie0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“as well as among effector candidates from other phytopathogenic fungi”
t0“oilseed rape stem canker”
Claim · model-written summary
Ecp11-1 expressing L. maculans transformants triggered immunity in oilseed rape genotypes carrying Rlm3.
- Taxon
- oilseed rapeBrassica napuse0
- Treatment
- transformants of L. maculans expressing one of these structural analogues, Ecp11-1e0
- Interactor
- L. maculansPlenodomus lingame0pathogen
- Gene
- Rlm3e0
- Outcome
- oilseed rape immunitye0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transformants of L. maculans expressing one of these structural analogues, Ecp11-1, triggered oilseed rape immunity in several genotypes carrying Rlm3”
Claim · model-written summary
AvrLm4-7 suppressed the resistance triggered by Ecp11-1.
- Taxon
- oilseed rapeBrassica napust0
- Interactor
- Leptosphaeria maculansPlenodomus lingame1pathogene0
- Gene
- AvrLm4-7e0
- Outcome
- this resistancee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this resistance could be suppressed by AvrLm4-7”
t0“oilseed rape stem canker”
e1“Leptosphaeria maculans”
The same questions in other papers
Plenodomus lingam · disease · Brassica napus (oilseed rape)Positive and negative results
1 in the opposite direction
- no effect
transgenic · disease · Brassica napus (oilseed rape)Results agree
6 papers in the same direction as this paper
- positive
- positive
- positive
3 papers more in this group
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.