Abstract
Strategies for plant resistance gene deployment aim to preserve their durability to highly adaptable fungal pathogens. While the pyramiding of resistance genes is often proposed as an effective way to increase their durability, molecular mechanisms by which the pathogen can overcome the resistance also are important aspects to take into account. Here, we report a counterexample where pyramiding of two resistance genes of Brassica napus, Rlm3 and Rlm7, matching the Leptosphaeria maculans avirulence genes AvrLm3 and AvrLm4-7, respectively, favored the selection of double-virulent isolates. We previously demonstrated that the presence of a functional AvrLm4-7 gene in an isolate masks the Rlm3-AvrLm3 recognition. Rlm7 was massively deployed in France since 2004. L. maculans populations were surveyed on a large scale (>7,600 isolates) over a period of 20 years, and resistance gene deployment at the regional scale was determined. Mutations in isolates overcoming both resistance genes were analyzed. All data indicated that the simultaneous success of Rlm7, the deployment of varieties pyramiding Rlm3 and Rlm7, along with the decrease in areas cultivated with Rlm3 only, contributed to the success of virulent isolates toward Rlm7, and more recently to both Rlm3 and Rlm7. Experimental field assays proved that resistance gene alternation was a better strategy compared with pyramiding in this context. Our study also illustrated an unusually high sequence diversification of AvrLm3 and AvrLm4-7 under such a selection pressure, and identified a few regions of the AvrLm4-7 protein involved in both its recognition by Rlm7 and in its AvrLm3-Rlm3 masking ability. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .
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Claims 7
Claim · model-written summary
Pyramiding Rlm3 and Rlm7 favored selection of double-virulent pathogen isolates.
- Taxon
- Brassica napus
_Brassica_napus_-_Habit.jpg?width=60)
Brassica napuse0 - Interactor
- Leptosphaeria maculans
Plenodomus lingame0pathogen - Gene
- Rlm3 and Rlm7e0
- Outcome
- selection of double-virulent isolatese0
- Direction
- favorede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Brassica_napus_-_Habit.jpg?width=500)
Verbatim
e0“pyramiding of two resistance genes of Brassica napus, Rlm3 and Rlm7, matching the Leptosphaeria maculans avirulence genes AvrLm3 and AvrLm4-7, respectively, favored the selection of double-virulent isolates”
Claim · model-written summary
Rlm7 success, pyramided varieties and reduced Rlm3-only cultivation contributed to increased Rlm7 virulence.
- Taxon
- Rapeseedt0
- Interactor
- Leptosphaeria maculansPlenodomus lingamt0pathogen
- Gene
- Rlm7e0
- Outcome
- success of virulent isolates toward Rlm7e0
- Direction
- successe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Leptosphaeria maculans Population Survey in France Suggests Pyramiding Rlm3 and Rlm7 in Rapeseed”
e0“the simultaneous success of Rlm7, the deployment of varieties pyramiding Rlm3 and Rlm7, along with the decrease in areas cultivated with Rlm3 only, contributed to the success of virulent isolates toward Rlm7”
Claim · model-written summary
The same deployment pattern later contributed to virulence against both Rlm3 and Rlm7.
- Taxon
- Rapeseedt0
- Interactor
- Leptosphaeria maculansPlenodomus lingamt0pathogen
- Gene
- Rlm3 and Rlm7t0
- Outcome
- both Rlm3 and Rlm7e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Leptosphaeria maculans Population Survey in France Suggests Pyramiding Rlm3 and Rlm7 in Rapeseed”
e0“and more recently to both Rlm3 and Rlm7”
Claim · model-written summary
Field assays found resistance-gene alternation better than pyramiding.
Verbatim
t0“Rapeseed”
e0“Experimental field assays proved that resistance gene alternation was a better strategy compared with pyramiding in this context.”
Claim · model-written summary
AvrLm3 showed unusually high sequence diversification under selection pressure.
- Taxon
- Leptosphaeria maculansPlenodomus lingamt0
- Gene
- AvrLm3e0
- Outcome
- sequence diversificatione0
- Direction
- unusually highe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Leptosphaeria maculans”
e0“an unusually high sequence diversification of AvrLm3 and AvrLm4-7 under such a selection pressure”
Claim · model-written summary
AvrLm4-7 showed unusually high sequence diversification under selection pressure.
- Taxon
- Leptosphaeria maculansPlenodomus lingamt0
- Gene
- AvrLm4-7e0
- Outcome
- sequence diversificatione0
- Direction
- unusually highe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Leptosphaeria maculans”
e0“an unusually high sequence diversification of AvrLm3 and AvrLm4-7 under such a selection pressure”
Claim · model-written summary
Regions of AvrLm4-7 protein involved in Rlm7 recognition and AvrLm3-Rlm3 masking were identified.
- Taxon
- Leptosphaeria maculansPlenodomus lingamt0
- Gene
- AvrLm4-7e0
- Outcome
- regions of the AvrLm4-7 protein involved in both its recognition by Rlm7 and in its AvrLm3-Rlm3 masking abilitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Leptosphaeria maculans”
e0“identified a few regions of the AvrLm4-7 protein involved in both its recognition by Rlm7 and in its AvrLm3-Rlm3 masking ability”