Allocating nitrogen away from a herbivore: A novel compensatory response to root herbivory

Beth A. Newingham, Ragan M. Callaway, Hormoz BassiriRad

Research output: Contribution to journalArticlepeer-review

Abstract

Centaurea maculosa, an invasive North American plant species, shows a high degree of tolerance to the root-boring biocontrol herbivore, Agapeta zoegana. For example, infested individuals of C. maculosa often exhibit more rigorous growth and reproduction compared with their non-infested counterparts. Compensatory responses to aboveground herbivores often involve increases in leaf area and/or photosynthetic capacity, but considerably less is known about root system compensatory responses to belowground herbivory. We used a 15N labeling approach to evaluate whether compensatory adjustments in N acquisition via changes in root morphology and/or physiological uptake capacity could explain the ability of C. maculosa to tolerate root herbivory. Root herbivory reduced whole plant N uptake by more than 30% and root uptake capacity by about 50%. Despite a marked reduction in N procurement, herbivory did not affect total biomass or shoot N status. Infested plants maintained shoot N status by shifting more of the acquired N from the root to the shoot. To our knowledge, shifting N allocation away from a root herbivore has not been reported and provides a plausible mechanism for the host plant to overcome an otherwise devastating effect of a root herbivore-induced N deficit.

Original languageEnglish
Pages (from-to)913-920
Number of pages8
JournalOecologia
Volume153
Issue number4
DOIs
StatePublished - Oct 2007

Keywords

  • Allocation
  • Biocontrol
  • Nitrogen
  • Root herbivory
  • Root uptake capacity

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