Vacuolar processing enzyme activates programmed cell death in the apical meristem inducing loss of apical dominance

Plant Cell Environ. 2017 Oct;40(10):2381-2392. doi: 10.1111/pce.13044. Epub 2017 Aug 25.


The potato (Solanum tuberosum L.) tuber is a swollen underground stem that can sprout in an apical dominance (AD) pattern. Bromoethane (BE) induces loss of AD and the accumulation of vegetative vacuolar processing enzyme (S. tuberosum vacuolar processing enzyme [StVPE]) in the tuber apical meristem (TAM). Vacuolar processing enzyme activity, induced by BE, is followed by programmed cell death in the TAM. In this study, we found that the mature StVPE1 (mVPE) protein exhibits specific activity for caspase 1, but not caspase 3 substrates. Optimal activity of mVPE was achieved at acidic pH, consistent with localization of StVPE1 to the vacuole, at the edge of the TAM. Downregulation of StVPE1 by RNA interference resulted in reduced stem branching and retained AD in tubers treated with BE. Overexpression of StVPE1 fused to green fluorescent protein showed enhanced stem branching after BE treatment. Our data suggest that, following stress, induction of StVPE1 in the TAM induces AD loss and stem branching.

Keywords: Solanum tuberosum (potato); apical dominance (AD); caspase; stem branching; tuber apical meristem (TAM); vacuolar processing enzyme (VPE).

MeSH terms

  • Apoptosis* / drug effects
  • Apoptosis* / genetics
  • Caspase 1 / metabolism
  • Cysteine Endopeptidases / metabolism*
  • Gene Expression Regulation, Plant / drug effects
  • Gene Silencing / drug effects
  • Green Fluorescent Proteins / metabolism
  • Hydrocarbons, Brominated / pharmacology
  • Hydrogen-Ion Concentration
  • Meristem / cytology*
  • Meristem / drug effects
  • Meristem / enzymology*
  • Meristem / genetics
  • Plant Tubers / drug effects
  • Plant Tubers / enzymology
  • Plant Tubers / genetics
  • Solanum tuberosum / drug effects
  • Solanum tuberosum / enzymology*
  • Solanum tuberosum / genetics


  • Hydrocarbons, Brominated
  • Green Fluorescent Proteins
  • Cysteine Endopeptidases
  • vacuolar processing enzyme
  • Caspase 1
  • bromoethane