Abstract
The successional dynamics of root-colonizing microbes are hypothesized to be critical to displacing fungal pathogens that can proliferate after the use of some herbicides. Applications of glyphosate in particular, which compromises the plant defense system by interfering with the production of aromatic amino acids, are thought to promote a buildup of root pathogens and can result in a "greenbridge" between weeds or volunteers and crop hosts. By planting 2 to 3 weeks after spraying, growers can avoid most negative impacts of the greenbridge by allowing pathogen populations to decline, but with the added cost of delayed planting dates. However, the specific changes in microbial communities during this period of root death and the microbial taxa likely to be involved in displacing pathogens are poorly characterized. Using high-throughput sequencing, we characterized fungal and oomycete communities in roots after applications of herbicides with different modes of action (glyphosate or clethodim) and tracked their dynamics over 3 weeks in both naturally infested soil and soil inoculated with Rhizoctonia solani AG-8. We found that many unexpected taxa were present at high relative abundance (e.g., Pythium volutum and Myrmecridium species) in live and dying wheat roots and may play an under-recognized role in greenbridge dynamics. Moreover, communities were highly dynamic over time and had herbicide-specific successional patterns, but became relatively stable by 2 weeks after herbicide application. Network analysis of communities over time revealed patterns of interactions among taxa that were both common and unique to each herbicide treatment and identified two primary groups of taxa with many positive associations within-groups but negative associations between-groups, suggesting that these groups are antagonistic to one another in dying roots and may play a role in displacing pathogen populations during greenbridge dynamics.
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Claims 6
Claim · model-written summary
Taxa such as Pythium volutum and Myrmecridium species were present at high relative abundance in live and dying wheat roots.
- Taxon
- Wheat
Triticum aestivumt0 - Organ / stage
- wheat rootse1
- Interactor
- Pythium volutumPythium volutume1other
- Second interactor
- Myrmecridium speciesMyrmecridiume1other
- Outcome
- relative abundancee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Glyphosate-Killed Wheat Roots”
e1“We found that many unexpected taxa were present at high relative abundance (e.g., Pythium volutum and Myrmecridium species) in live and dying wheat roots”
Claim · model-written summary
Root fungal and oomycete communities were highly dynamic over time, with herbicide-specific successional patterns.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- herbicide applicatione2
- Outcome
- herbicide-specific successional patternse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Glyphosate-Killed Wheat Roots”
e2“communities were highly dynamic over time and had herbicide-specific successional patterns, but became relatively stable by 2 weeks after herbicide application”
Claim · model-written summary
Root communities became relatively stable by 2 weeks after herbicide application.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- herbicide applicatione2
- Outcome
- relatively stablee2
- Value
- 2 weekse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Glyphosate-Killed Wheat Roots”
e2“communities were highly dynamic over time and had herbicide-specific successional patterns, but became relatively stable by 2 weeks after herbicide application”
Claim · model-written summary
Network analysis revealed interaction patterns among taxa that were both common and unique to each herbicide treatment.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- each herbicide treatmente3
- Outcome
- patterns of interactions among taxae3
- Qualifier
- common and uniquee3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Glyphosate-Killed Wheat Roots”
e3“Network analysis of communities over time revealed patterns of interactions among taxa that were both common and unique to each herbicide treatment”
Claim · model-written summary
Two groups of taxa showed many positive associations within groups but negative associations between groups in dying roots.
- Taxon
- WheatTriticum aestivumt0
- Organ / stage
- dying rootse4
- Outcome
- associations between-groupse4
- Direction
- negativee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Glyphosate-Killed Wheat Roots”
e4“identified two primary groups of taxa with many positive associations within-groups but negative associations between-groups, suggesting that these groups are antagonistic to one another in dying roots”
Claim · model-written summary
The two taxa groups may be antagonistic to one another and may play a role in displacing pathogen populations during greenbridge dynamics.
- Taxon
- WheatTriticum aestivumt0
- Organ / stage
- dying rootse4
- Outcome
- displacing pathogen populationse5
- Qualifier
- antagonistic to one anothere4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Glyphosate-Killed Wheat Roots”
e4“suggesting that these groups are antagonistic to one another in dying roots”
e5“may play a role in displacing pathogen populations during greenbridge dynamics”