A genetic framework for H2O2 induced cell death in Arabidopsis thaliana.
BACKGROUND
To survive in a changing environment plants constantly monitor their surroundings. In response to several stresses and during photorespiration plants use reactive oxygen species as signaling molecules. The Arabidopsis thaliana catalase2 (cat2) mutant lacks a peroxisomal catalase and under photorespiratory conditions accumulates H2O2, which leads to activation of cell death.


METHODS
A cat2 double mutant collection was generated through crossing and scored for cell death in different assays. Selected double mutants were further analyzed for photosynthetic performance and H2O2 accumulation.


RESULTS
We used a targeted mutant analysis with more than 50 cat2 double mutants to investigate the role of stress hormones and other defense regulators in H2O2-mediated cell death. Several transcription factors (AS1, MYB30, MYC2, WRKY70), cell death regulators (RCD1, DND1) and hormone regulators (AXR1, ERA1, SID2, EDS1, SGT1b) were essential for execution of cell death in cat2. Genetic loci required for cell death in cat2 was compared with regulators of cell death in spontaneous lesion mimic mutants and led to the identification of a core set of plant cell death regulators. Analysis of gene expression data from cat2 and plants undergoing cell death revealed similar gene expression profiles, further supporting the existence of a common program for regulation of plant cell death.


CONCLUSIONS
Our results provide a genetic framework for further study on the role of H2O2 in regulation of cell death. The hormones salicylic acid, jasmonic acid and auxin, as well as their interaction, are crucial determinants of cell death regulation.
Division of Plant Biology, Department of Biosciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland. eve.kaurilind@ut.ee.|Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia. eve.kaurilind@ut.ee.
Eve
E
Kaurilind
Division of Plant Biology, Department of Biosciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland. enjun.xu@helsinki.fi.
Enjun
E
Xu
Division of Plant Biology, Department of Biosciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland. mikael.brosche@helsinki.fi.|Institute of Technology, University of Tartu, Nooruse 1, Tartu, 50411, Estonia. mikael.brosche@helsinki.fi.
Mikael
M
Brosché
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D002374:Catalase / Q000096:biosynthesis; D016923:Cell Death / Q000187:drug effects / Q000235:genetics*; D003517:Cyclopentanes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007210:Indoleacetic Acids / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics*; D054883:Oxylipins / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
D003517:Cyclopentanes; D007210:Indoleacetic Acids; D054883:Oxylipins; D017382:Reactive Oxygen Species; C011006:jasmonic acid; D006861:Hydrogen Peroxide; D002374:Catalase; D020156:Salicylic Acid