Interspecific variation in crop and weed responses to arbuscular mycorrhizal fungal community highlights opportunities for weed biocontrol

Authors: LI, MENG - UNIVERSITY OF CALIFORNIA, DAVIS; JORDAN, NICHOLAS - UNIVERSITY OF MINNESOTA; KOIDE, ROGER - BRIGHAM YOUNG UNIVERSITY; YANNARELL, ANTHONY - UNIVERSITY OF ILLINOIS; DAVIS, ADAM

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/2019
Publication Date: 5/29/2019
Citation: Li, M., Jordan, N.R., Koide, R.T., Yannarell, A.C., Davis, A.S. 2019. Interspecific variation in crop and weed responses to arbuscular mycorrhizal fungal community highlights opportunities for weed biocontrol. Applied Soil Ecology. 142:23-42. https://doi.org/10.1016/j.apsoil.2019.05.016.
DOI: https://doi.org/10.1016/j.apsoil.2019.05.016

Interpretive Summary: The rapid, widespread proliferation of herbicide resistant weeds threatens food security, and requires the development of new approaches to weed management that are less reliant on herbicides. Biological control of agricultural weeds through management of soil microbes, such as arbuscular mycorrhizal fungi (AMF), offers one such approach, but there are considerable knowledge gaps that must be addressed before it can provide reliable weed control. We examined root AMF communities of four weed species and one crop species in a field experiment with contrasting tillage and cover cropping treatments in Illinois, USA. Our objectives were to quantify the impact of AMF on the growth of weed and crop species, to assess the relative contributions of tillage, cover cropping, and plant identity on AMF community structures, and to characterize the co-occurrence patterns of AMF species in weed and crop roots. Our results showed that effects of AMF species on crop and weed growth varied widely depending on plant identity, and several AMF taxa had species-specific negative effects on weeds but not on the crop species. We propose that AMF taxa that have selective suppressing effects on weeds but not on the crop species may serve as candidates for developing new strategies for weed biocontrol as part of integrated weed management. Future approaches to weed management based on direct augmentation (e.g., inoculation with particular AMF strains) of the weed-suppressing AMF taxa may hold some promise, and our methods will provide important insights for the selection of such AMF species.

Technical Abstract: New, non-chemical weed suppression methods are needed to support multi-tactic integrated weed management programs that reduce reliance on herbicides. One such approach is to manage arbuscular mycorrhizal fungi (AMF) communities to enhance their weed biocontrol potential. Successful implementation will require a better understanding of AMF-crop-weed relationships under field conditions, especially in the face of soil disturbances imposed by agricultural practices. We examined root AMF communities of four weed species and one crop species in a field experiment with contrasting tillage and cover cropping treatments in Illinois, USA. Our objectives were to quantify the impact of AMF on the growth of weed and crop species, to assess the relative contributions of tillage, cover cropping, and plant identity on AMF community structures, and to characterize the co-occurrence patterns of AMF species in weed and crop roots. Our results showed that effects of AMF species on crop and weed growth varied widely depending on plant identity, and several AMF taxa had species-specific negative effects on weeds but not on the crop species. In addition, crop and weed identity was the primary factor affecting root AMF community structure and co-occurrence patterns, whereas effects of tillage and cover cropping were relatively limited. We propose that AMF taxa that have selective suppressing effects on weeds but not on the crop species may serve as candidates for developing new strategies for weed biocontrol as part of integrated weed management. Future approaches to weed management based on direct augmentation (e.g., inoculation with particular AMF strains) of the weed-suppressing AMF taxa may hold some promise, and our methods will provide important insights for the selection of such AMF species.