Rhizobium leguminosarum bv. viciae 3841 Adapts to 2,4-Dichlorophenoxyacetic Acid with "Auxin-Like" Morphological Changes, Cell Envelope Remodeling and Upregulation of Central Metabolic Pathways.
There is a growing need to characterize the effects of environmental stressors at the molecular level on model organisms with the ever increasing number and variety of anthropogenic chemical pollutants. The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), as one of the most widely applied pesticides in the world, is one such example. This herbicide is known to have non-targeted undesirable effects on humans, animals and soil microbes, but specific molecular targets at sublethal levels are unknown. In this study, we have used Rhizobium leguminosarum bv. viciae 3841 (Rlv) as a nitrogen fixing, beneficial model soil organism to characterize the effects of 2,4-D. Using metabolomics and advanced microscopy we determined specific target pathways in the Rlv metabolic network and consequent changes to its phenotype, surface ultrastructure, and physical properties during sublethal 2,4-D exposure. Auxin and 2,4-D, its structural analogue, showed common morphological changes in vitro which were similar to bacteroids isolated from plant nodules, implying that these changes are related to bacteroid differentiation required for nitrogen fixation. Rlv showed remarkable adaptation capabilities in response to the herbicide, with changes to integral pathways of cellular metabolism and the potential to assimilate 2,4-D with consequent changes to its physical and structural properties. This study identifies biomarkers of 2,4-D in Rlv and offers valuable insights into the mode-of-action of 2,4-D in soil bacteria.
Department of Chemistry and Biochemistry, University of Regina, 3737 Wascana Parkway, Regina, SK, S4S 0A2 Canada.
Supriya V
SV
Bhat
Department of Biological Sciences, University of Calgary, 2500 University Dr, NW Calgary, AB, T2N 1N4 Canada.
Sean C
SC
Booth
Department of Chemistry and Biochemistry, University of Regina, 3737 Wascana Parkway, Regina, SK, S4S 0A2 Canada.
Seamus G K
SG
McGrath
Department of Chemistry and Biochemistry, University of Regina, 3737 Wascana Parkway, Regina, SK, S4S 0A2 Canada.
Tanya E S
TE
Dahms
D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology*; D000220:Adaptation, Biological; D006540:Herbicides / Q000494:pharmacology*; D007210:Indoleacetic Acids / Q000737:chemistry / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D055432:Metabolomics; D016961:Rhizobium leguminosarum / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D012988:Soil Microbiology
D006540:Herbicides; D007210:Indoleacetic Acids; D015084:2,4-Dichlorophenoxyacetic Acid