Caffeine-Induced Premature Chromosome Condensation Results in the Apoptosis-Like Programmed Cell Death in Root Meristems of Vicia faba

PLoS One. 2015 Nov 6;10(11):e0142307. doi: 10.1371/journal.pone.0142307. eCollection 2015.

Abstract

We have demonstrated that the activation of apoptosis-like programmed cell death (AL-PCD) was a secondary result of caffeine (CF) induced premature chromosome condensation (PCC) in hydroxyurea-synchronized Vicia faba root meristem cells. Initiation of the apoptotic-like cell degradation pathway seemed to be the result of DNA damage generated by treatment with hydroxyurea (HU) [double-stranded breaks (DSBs) mostly] and co-treatment with HU/CF [single-stranded breaks (SSBs) mainly]. A single chromosome comet assay was successfully used to study different types of DNA damage (neutral variant-DSBs versus alkaline-DSBs or SSBs). The immunocytochemical detection of H2AXS139Ph and PARP-2 were used as markers for DSBs and SSBs, respectively. Acridine orange and ethidium bromide (AO/EB) were applied for quantitative immunofluorescence measurements of dead, dying and living cells. Apoptotic-type DNA fragmentation and positive TUNEL reaction finally proved that CF triggers AL-PCD in stressed V. faba root meristem cells. In addition, the results obtained under transmission electron microscopy (TEM) further revealed apoptotic-like features at the ultrastructural level of PCC-type cells: (i) extensive vacuolization; (ii) abnormal chromatin condensation, its marginalization and concomitant degradation; (iii) formation of autophagy-like vesicles (iv) protoplast shrinkage (v) fragmentation of cell nuclei and (vi) extensive degeneration of the cells. The results obtained have been discussed with respect to the vacuolar/autolytic type of plant-specific AL-PCD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caffeine / pharmacology*
  • Cell Death / drug effects
  • Chromosomes, Plant / metabolism*
  • DNA Damage / drug effects
  • Humans
  • Hydroxyurea / pharmacology
  • Meristem / cytology
  • Meristem / drug effects*
  • Plant Roots / cytology
  • Vacuoles / drug effects
  • Vicia faba / cytology*

Substances

  • Caffeine
  • Hydroxyurea

Grants and funding

The work was funded by 'POMOST' fellowship from the Foundation for Polish Science (contract no. POMOST/2011-4/8).