title: An inositolphosphorylceramide synthase is involved in regulation of plant programmed cell death associated with defense in Arabidopsis.
abstract: The Arabidopsis thaliana resistance gene RPW8 triggers the hypersensitive response (HR) to restrict powdery mildew infection via the salicylic acid-dependent signaling pathway. To further understand how RPW8 signaling is regulated, we have conducted a genetic screen to identify mutations enhancing RPW8-mediated HR-like cell death (designated erh). Here, we report the isolation and characterization of the Arabidopsis erh1 mutant, in which the At2g37940 locus is knocked out by a T-DNA insertion. Loss of function of ERH1 results in salicylic acid accumulation, enhanced transcription of RPW8 and RPW8-dependent spontaneous HR-like cell death in leaf tissues, and reduction in plant stature. Sequence analysis suggests that ERH1 may encode the long-sought Arabidopsis functional homolog of yeast and protozoan inositolphosphorylceramide synthase (IPCS), which converts ceramide to inositolphosphorylceramide. Indeed, ERH1 is able to rescue the yeast aur1 mutant, which lacks the IPCS, and the erh1 mutant plants display reduced ( approximately 53% of wild type) levels of leaf IPCS activity, indicating that ERH1 encodes a plant IPCS. Consistent with its biochemical function, the erh1 mutation causes ceramide accumulation in plants expressing RPW8. These data reinforce the concept that sphingolipid metabolism (specifically, ceramide accumulation) plays an important role in modulating plant programmed cell death associated with defense.
authors.affiliation: Center for Biosystems Research, University of Maryland Biotechnology Institute, Rockville, Maryland 20850, USA.
authors.forename: Wenming
authors.initials: W
authors.lastname: Wang
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Yang
authors.forename: Samantha
authors.initials: S
authors.lastname: Tangchaiburana
authors.forename: Roland
authors.initials: R
authors.lastname: Ndeh
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Markham
authors.forename: Yoseph
authors.initials: Y
authors.lastname: Tsegaye
authors.forename: Teresa M
authors.initials: TM
authors.lastname: Dunn
authors.forename: Guo-Liang
authors.initials: GL
authors.lastname: Wang
authors.forename: Maria
authors.initials: M
authors.lastname: Bellizzi
authors.forename: James F
authors.initials: JF
authors.lastname: Parsons
authors.forename: Danielle
authors.initials: D
authors.lastname: Morrissey
authors.forename: Janis E
authors.initials: JE
authors.lastname: Bravo
authors.forename: Daniel V
authors.initials: DV
authors.lastname: Lynch
authors.forename: Shunyuan
authors.initials: S
authors.lastname: Xiao
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001203:Ascomycota; D016923:Cell Death; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D006602:Hexosyltransferases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D010641:Phenotype; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D018749:RNA, Plant / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D018749:RNA, Plant; C036483:T-DNA; D006602:Hexosyltransferases; C088714:phosphatidylinositol-ceramide phosphoinositol transferase