MPK6, sphinganine and the LCB2a gene from serine palmitoyltransferase are required in the signaling pathway that mediates cell death induced by long chain bases in Arabidopsis

New Phytol. 2011 Sep;191(4):943-57. doi: 10.1111/j.1469-8137.2011.03727.x. Epub 2011 Apr 27.

Abstract

Long chain bases (LCBs) are sphingolipid intermediates acting as second messengers in programmed cell death (PCD) in plants. Most of the molecular and cellular features of this signaling function remain unknown. We induced PCD conditions in Arabidopsis thaliana seedlings and analyzed LCB accumulation kinetics, cell ultrastructure and phenotypes in serine palmitoyltransferase (spt), mitogen-activated protein kinase (mpk), mitogen-activated protein phosphatase (mkp1) and lcb-hydroxylase (sbh) mutants. The lcb2a-1 mutant was unable to mount an effective PCD in response to fumonisin B1 (FB1), revealing that the LCB2a gene is essential for the induction of PCD. The accumulation kinetics of LCBs in wild-type (WT) and lcb2a-1 plants and reconstitution experiments with sphinganine indicated that this LCB was primarily responsible for PCD elicitation. The resistance of the null mpk6 mutant to manifest PCD on FB1 and sphinganine addition and the failure to show resistance on pathogen infection and MPK6 activation by FB1 and LCBs indicated that MPK6 mediates PCD downstream of LCBs. This work describes MPK6 as a novel transducer in the pathway leading to LCB-induced PCD in Arabidopsis, and reveals that sphinganine and the LCB2a gene are required in a PCD process that operates as one of the more effective strategies used as defense against pathogens in plants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / drug effects
  • Arabidopsis / enzymology
  • Arabidopsis / genetics*
  • Arabidopsis / immunology
  • Arabidopsis / microbiology
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Cell Death*
  • Chloroplasts / metabolism
  • DNA Fragmentation
  • Disease Resistance
  • Fumonisins / pharmacology
  • Genotype
  • Mitogen-Activated Protein Kinases / genetics
  • Mitogen-Activated Protein Kinases / metabolism*
  • Mutagenesis, Insertional
  • Phenotype
  • Protein Tyrosine Phosphatases
  • Pseudomonas syringae / immunology
  • Pseudomonas syringae / pathogenicity
  • Seedlings / drug effects
  • Seedlings / microbiology
  • Seedlings / ultrastructure
  • Serine C-Palmitoyltransferase / genetics
  • Serine C-Palmitoyltransferase / metabolism*
  • Signal Transduction*
  • Sphingolipids / metabolism
  • Sphingosine / analogs & derivatives*
  • Sphingosine / genetics
  • Sphingosine / metabolism

Substances

  • Arabidopsis Proteins
  • Fumonisins
  • Sphingolipids
  • fumonisin B1
  • Lcb2 protein, Arabidopsis
  • Serine C-Palmitoyltransferase
  • MPK6 protein, Arabidopsis
  • Mitogen-Activated Protein Kinases
  • MKP1 protein, Arabidopsis
  • Protein Tyrosine Phosphatases
  • Sphingosine
  • safingol