A MYB transcription factor regulates very-long-chain fatty acid biosynthesis for activation of the hypersensitive cell death response in Arabidopsis.
Plant immune responses to pathogen attack include the hypersensitive response (HR), a form of programmed cell death occurring at invasion sites. We previously reported on Arabidopsis thaliana MYB30, a transcription factor that acts as a positive regulator of a cell death pathway conditioning the HR. Here, we show by microarray analyses of Arabidopsis plants misexpressing MYB30 that the genes encoding the four enzymes forming the acyl-coA elongase complex are putative MYB30 targets. The acyl-coA elongase complex synthesizes very-long-chain fatty acids (VLCFAs), and the accumulation of extracellular VLCFA-derived metabolites (leaf epidermal wax components) was affected in MYB30 knockout mutant and overexpressing lines. In the same lines, a lipid extraction procedure allowing high recovery of sphingolipids revealed changes in VLCFA contents that were amplified in response to inoculation. Finally, the exacerbated HR phenotype of MYB30-overexpressing lines was altered by the loss of function of the acyl-ACP thioesterase FATB, which causes severe defects in the supply of fatty acids for VLCFA biosynthesis. Based on these findings, we propose a model in which MYB30 modulates HR via VLCFAs by themselves, or VLCFA derivatives, as cell death messengers in plants.
Raffaele
Sylvain
S
Unité Mixte de Recherche 2594/441, 31320 Castanet-Tolosan cedex, France.
Vailleau
Fabienne
F
Léger
Amandine
A
Joubès
Jérôme
J
Miersch
Otto
O
Huard
Carine
C
Blée
Elisabeth
E
Mongrand
Sébastien
S
Domergue
Frédéric
F
Roby
Dominique
D
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D016923:Cell Death / Q000235:genetics; D005227:Fatty Acids / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant; D008954:Models, Biological; D020411:Oligonucleotide Array Sequence Analysis; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
D029681:Arabidopsis Proteins; D005227:Fatty Acids; C500589:Myb protein, Arabidopsis; D014157:Transcription Factors