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Title: Elevated carbon dioxide spurs reciprocal positive effects between a plant virus and an arbuscular mycorrhizal fungus

item RUA, MEGAN - University Of North Carolina
item UMBANHOWAR, JAMES - University Of North Carolina
item HU, SHUIJIN - North Carolina State University
item Burkey, Kent
item MITCHELL, CHARLES - University Of North Carolina

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2013
Publication Date: 3/12/2013
Citation: Rua, M., Umbanhowar, J., Hu, S., Burkey, K.O., Mitchell, C. 2013. Elevated carbon dioxide spurs reciprocal positive effects between a plant virus and an arbuscular mycorrhizal fungus. New Phytologist. 199:541-549.

Interpretive Summary: It is well known that elevated carbon dioxide stimulates plant productivity through increases in photosynthesis. This effect is mediated by complex processes beyond the obvious benefit of providing more carbon for plant growth. Such processes include the simultaneous interactions between plants as host species and naturally occurring beneficial microbes as well as pathogens. In this study, elevated carbon dioxide was found to interact with soil phosphorus supply and viral infection to enhance the association of beneficial mycorrhizal fungi with the roots of two grass species. The reproduction of the aphid vector used to infect plants with the virus was also dependent on complex interactions between the presence of the virus, carbon dioxide concentration, and grass species. The results suggest that projected increases in atmospheric carbon dioxide will likely alter the interactions between plants and the microbes that associate with them.

Technical Abstract: Plants form ubiquitous associations with animals and microbes. These interactions range from parasitism to mutualism, depending partly on resource supplies that are being altered by global change. While many studies have considered the individual effects of pathogens and mutualists on their hosts, few studies have investigated interactions among microbial mutualists, pathogens and pathogen vectors in the context of global change. Here we experimentally test the interactive effects of increased atmospheric CO2 and soil phosphorus on two wild grasses, mycorrhizal fungi, aphids, and an aphid-transmitted virus. Virus infection and phosphorus addition increased mycorrhizal colonization for plants grown under elevated CO2. Both mycorrhizal association and phosphorus addition increased viral titer. Aphid reproduction was influenced by complex interactions among plant resources and microbial associations. Our research indicates that these mutualists, herbivores, and pathogens interact to alter each other’s success, and predicts these interactions will respond to changes in resource availability under global change.