title: Cell death patterns in Arabidopsis cells subjected to four physiological stressors indicate multiple signalling pathways and cell cycle phase specificity.
abstract: Corpse morphology, nuclear DNA fragmentation, expression of senescence-associated genes (SAG) and cysteine protease profiles were investigated to understand cell death patterns in a cell cycle-synchronised Arabidopsis thaliana cell suspension culture treated with four physiological stressors in the late G2 phase. Within 4 h of treatment, polyethylene glycol (PEG, 20 %), mannose (100 mM) and hydrogen peroxide (2 mM) caused DNA fragmentation coinciding with cell permeability to Evans Blue (EB) and produced corpse morphology corresponding to apoptosis-like programmed cell death (AL-PCD) with cytoplasmic retraction from the cell wall. Ethylene (8 mL per 250-mL flask) caused permeability of cells to EB without concomitant nuclear DNA fragmentation and cytoplasmic retraction, suggesting necrotic cell death. Mannose inducing glycolysis block and PEG causing dehydration resulted in relatively similar patterns of upregulation of SAG suggesting similar cell death signalling pathways for these two stress factors, whereas hydrogen peroxide caused unique patterns indicating an alternate pathway for cell death induced by oxidative stress. Ethylene did not cause appreciable changes in SAG expression, confirming necrotic cell death. Expression of AtDAD, BoMT1 and AtSAG2 genes, previously shown to be associated with plant senescence, also changed rapidly during AL-PCD in cultured cells. The profiles of nine distinct cysteine protease-active bands ranging in size from ca. 21.5 to 38.5 kDa found in the control cultures were also altered after treatment with the four stressors, with mannose and PEG again producing similar patterns. Results also suggest that cysteine proteases may have a role in necrotic cell death.
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North, New Zealand. ranjith.pathirana@plantandfood.co.nz.
authors.forename: Ranjith
authors.initials: R
authors.lastname: Pathirana
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North, New Zealand.|NZ Avocado, Level 5 Harrington House, 32 Harington Street, Tauranga, 3110, New Zealand.
authors.forename: Phillip
authors.initials: P
authors.lastname: West
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North, New Zealand.
authors.forename: Duncan
authors.initials: D
authors.lastname: Hedderley
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North, New Zealand.
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Eason
mesh_terms: D016590:Aphidicolin / Q000494:pharmacology; D017360:Arabidopsis / Q000166:cytology* / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D016923:Cell Death / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D057056:Cysteine Proteases / Q000378:metabolism; D004171:Diploidy; D005434:Flow Cytometry; D016195:G2 Phase / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D006657:Histones / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D059828:Plant Cells / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D013997:Time Factors
chemical_list: D029681:Arabidopsis Proteins; D006657:Histones; D016590:Aphidicolin; D057056:Cysteine Proteases
keywords: Cysteine protease; Ethylene; Gene expression; Mannose; Necrosis; Osmotic stress; Oxidative stress; Programmed cell death