title: LESION SIMULATING DISEASE 1 is required for acclimation to conditions that promote excess excitation energy.
abstract: The lsd1 mutant of Arabidopsis fails to limit the boundaries of hypersensitive cell death response during avirulent pathogen infection and initiates unchecked lesions in long day photoperiod giving rise to the runaway cell death (rcd) phenotype. We link here the initiation and propagation of rcd to the activity of photosystem II, stomatal conductance and ultimately to photorespiratory H(2)O(2). A cross of lsd1 with the chlorophyll a/b binding harvesting-organelle specific (designated cao) mutant, which has a reduced photosystem II antenna, led to reduced lesion formation in the lsd1/cao double mutant. This lsd1 mutant also had reduced stomatal conductance and catalase activity in short-day permissive conditions and induced H(2)O(2) accumulation followed by rcd when stomatal gas exchange was further impeded. All of these traits depended on the defense regulators EDS1 and PAD4. Furthermore, nonphotorespiratory conditions retarded propagation of lesions in lsd1. These data suggest that lsd1 failed to acclimate to light conditions that promote excess excitation energy (EEE) and that LSD1 function was required for optimal catalase activity. Through this regulation LSD1 can influence the effectiveness of photorespiration in dissipating EEE and consequently may be a key determinant of acclimatory processes. Salicylic acid, which induces stomatal closure, inhibits catalase activity and triggers the rcd phenotype in lsd1, also impaired acclimation of wild-type plants to conditions that promote EEE. We propose that the roles of LSD1 in light acclimation and in restricting pathogen-induced cell death are functionally linked.
authors.affiliation: Department of Botany, Stockholm University, Stockholm SE-106 91, Sweden.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Mateo
authors.forename: Per
authors.initials: P
authors.lastname: Mühlenbock
authors.forename: Christine
authors.initials: C
authors.lastname: Rustérucci
authors.forename: Christine Chi-Chen
authors.initials: CC
authors.lastname: Chang
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Miszalski
authors.forename: Barbara
authors.initials: B
authors.lastname: Karpinska
authors.forename: Jane E
authors.initials: JE
authors.lastname: Parker
authors.forename: Philip M
authors.initials: PM
authors.lastname: Mullineaux
authors.forename: Stanislaw
authors.initials: S
authors.lastname: Karpinski
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D016923:Cell Death / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D017343:Genes, Plant; D008027:Light; D009154:Mutation; D044742:Peronospora / Q000472:pathogenicity; D010641:Phenotype; D045332:Photosystem II Protein Complex / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D018744:DNA, Plant; D004268:DNA-Binding Proteins; C104920:LSD1 protein, Arabidopsis; D045332:Photosystem II Protein Complex; D014157:Transcription Factors; D002374:Catalase; D020156:Salicylic Acid