The xipotl mutant of Arabidopsis reveals a critical role for phospholipid metabolism in root system development and epidermal cell integrity.
Phosphocholine (PCho) is an essential metabolite for plant development because it is the precursor for the biosynthesis of phosphatidylcholine, which is the major lipid component in plant cell membranes. The main step in PCho biosynthesis in Arabidopsis thaliana is the triple, sequential N-methylation of phosphoethanolamine, catalyzed by S-adenosyl-l-methionine:phosphoethanolamine N-methyltransferase (PEAMT). In screenings performed to isolate Arabidopsis mutants with altered root system architecture, a T-DNA mutagenized line showing remarkable alterations in root development was isolated. At the seedling stage, the mutant phenotype is characterized by a short primary root, a high number of lateral roots, and short epidermal cells with aberrant morphology. Genetic and biochemical characterization of this mutant showed that the T-DNA was inserted at the At3g18000 locus (XIPOTL1), which encodes PEAMT (XIPOTL1). Further analyses revealed that inhibition of PCho biosynthesis in xpl1 mutants not only alters several root developmental traits but also induces cell death in root epidermal cells. Epidermal cell death could be reversed by phosphatidic acid treatment. Taken together, our results suggest that molecules produced downstream of the PCho biosynthesis pathway play key roles in root development and act as signals for cell integrity.
Departamento de Ingeniería Genética Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional Unidad Irapuato, Apartado Postal 629 36500 Irapuato, Guanajuato, Mexico.
Alfredo
A
Cruz-Ramírez
José
J
López-Bucio
Gabriel
G
Ramírez-Pimentel
Andrés
A
Zurita-Silva
Lenin
L
Sánchez-Calderon
Enrique
E
Ramírez-Chávez
Emmanuel
E
González-Ortega
Luis
L
Herrera-Estrella
D017360:Arabidopsis / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death / Q000502:physiology; D002794:Choline / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D017403:In Situ Hybridization; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010712:Phosphatidic Acids / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism*; D050918:Phosphatidylethanolamine N-Methyltransferase; D019441:Plant Epidermis / Q000166:cytology* / Q000502:physiology; D018517:Plant Roots / Q000033:anatomy & histology / Q000254:growth & development*
D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; C036483:T-DNA; D008780:Methyltransferases; C102844:phosphoethanolamine methyltransferase; D050918:Phosphatidylethanolamine N-Methyltransferase; D002794:Choline