Ontogenetic contingency of tolerance mechanisms in response to apical damage

Michal Gruntman*, Ariel Novoplansky

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Background and AimsPlants are able to tolerate tissue loss through vigorous branching which is often triggered by release from apical dominance and activation of lateral meristems. However, damage-induced branching might not be a mere physiological outcome of released apical dominance, but an adaptive response to environmental signals, such as damage timing and intensity. Here, branching responses to both factors were examined in the annual plant Medicago truncatula.MethodsBranching patterns and allocation to reproductive traits were examined in response to variable clipping intensities and timings in M. truncatula plants from two populations that vary in the onset of reproduction. Phenotypic selection analysis was used to evaluate the strength and direction of selection on branching under the damage treatments.Key ResultsPlants of both populations exhibited an ontogenetic shift in tolerance mechanisms: while early damage induced greater meristem activation, late damage elicited investment in late-determined traits, including mean pod and seed biomass, and supported greater germination rates. Severe damage mostly elicited simultaneous development of multiple-order lateral branches, but this response was limited to early damage. Selection analyses revealed positive directional selection on branching in plants under early- compared with late- or no-damage treatments.ConclusionsThe results demonstrate that damage-induced meristem activation is an adaptive response that could be modified according to the plants developmental stage, severity of tissue loss and their interaction, stressing the importance of considering these effects when studying plastic responses to apical damage.

Original languageEnglish
Pages (from-to)965-973
Number of pages9
JournalAnnals of Botany
Issue number5
StatePublished - Oct 2011
Externally publishedYes


  • Apical dominance
  • Medicago truncatula
  • branching
  • clipping
  • compensatory growth
  • herbivory
  • meristem activation
  • ontogeny
  • tolerance


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