Plant and Soil

, Volume 323, Issue 1, pp 187–196

Plant–rhizobia mutualism influences aphid abundance on soybean

Authors

  • Jennifer M. Dean
    • Center for Chemical EcologyThe Pennsylvania State University
  • Mark C. Mescher
    • Center for Chemical EcologyThe Pennsylvania State University
    • Center for Chemical EcologyThe Pennsylvania State University
Regular Article

DOI: 10.1007/s11104-009-9924-1

Cite this article as:
Dean, J.M., Mescher, M.C. & De Moraes, C.M. Plant Soil (2009) 323: 187. doi:10.1007/s11104-009-9924-1

Abstract

The mutualism between legumes and nitrogen-fixing soil bacteria (rhizobia) is a key feature of many ecological and agricultural systems, yet little is known about how this relationship affects aboveground interactions between plants and herbivores. We investigated the effects of the rhizobia mutualism on the abundance of a specialized legume herbivore on soybean plants. In a field experiment, soybean aphid (Aphis glycines) abundances were measured on plants (Glycine max) that were either (1) treated with a commercial rhizobial inoculant, (2) associating solely with naturally occurring rhizobia, or (3) given nitrogen fertilizer. Plants associating with naturally occurring rhizobia strains exhibited lower aphid population densities compared to those inoculated with a commercial rhizobial preparation or given nitrogen fertilizer. Genetic analyses of rhizobia isolates cultured from field plants revealed that the commercial rhizobia strains were phylogenetically distinct from naturally occurring strains. Plant size, leaf nitrogen concentration, and nodulation density were similar among rhizobia-associated treatments and did not explain the observed differences in aphid abundance. Our results demonstrate that plant–rhizobia interactions influence plant resistance to insect herbivores and that some rhizobia strains confer greater resistance to their mutualist partners than do others.

Keywords

Soybean (Glycine max)Rhizobia (Bradyrhizobium japonicum)Soybean aphis (Aphis glycines)Plant resistance

Abbreviations

CR

commercial rhizobia

DAP

days after planting

F

fertilized (with N)

N

nitrogen

NR

naturally occurring rhizobia

Copyright information

© Springer Science+Business Media B.V. 2009