RESUMO
We describe lacerata (lcr) mutants of Arabidopsis, which display various developmental abnormalities, including postgenital organ fusions, and report cloning of the LCR gene by using the maize transposon Enhancer/Suppressor-mutator (En/Spm). The pleiotropic mutant phenotype could be rescued by genetic complementation of lcr mutants with the wild-type LCR gene. The LCR gene encodes a cytochrome P450 monooxygenase, CYP86A8, which catalyzes omega-hydroxylation of fatty acids ranging from C12 to C18:1, as demonstrated by expression of the gene in yeast. Although palmitic and oleic acids were efficient substrates for LCR, 9,10-epoxystearate was not metabolized. Taken together with previous studies, our findings indicate that LCR-dependent omega-hydroxylation of fatty acids could be implicated in the biosynthesis of cutin in the epidermis and in preventing postgenital organ fusions. Strikingly, the same pathway seems to control trichome differentiation, the establishment of apical dominance, and senescence in plants.
Assuntos
Proteínas de Arabidopsis , Arabidopsis/genética , Sistema Enzimático do Citocromo P-450/genética , Ácidos Graxos/metabolismo , Genes de Plantas , Oxigenases de Função Mista/genética , Proteínas de Plantas/genética , Alelos , Sequência de Aminoácidos , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Sequência de Bases , Diferenciação Celular , Sistema Enzimático do Citocromo P-450/fisiologia , Elementos de DNA Transponíveis/genética , Teste de Complementação Genética , Hidroxilação , Lipídeos de Membrana/biossíntese , Oxigenases de Função Mista/fisiologia , Dados de Sequência Molecular , Morfogênese , Fenótipo , Epiderme Vegetal/metabolismo , Proteínas de Plantas/fisiologia , Plantas Geneticamente Modificadas , Proteínas Recombinantes de Fusão/metabolismo , Saccharomyces cerevisiae/metabolismo , Transdução de SinaisRESUMO
We report the isolation of the FIDDLEHEAD (FDH) gene of Arabidopsis by transposon tagging. Three mutant alleles of FDH carrying insertions of the Enhancer/Suppressor-mutator transposon and one stable allele with a transposon footprint were generated in the Arabidopsis ecotype Columbia genetic background. Closer examination of the adaxial epidermis of rosette leaves revealed that in addition to provoking the previously described fusion phenotype in leaves and floral organs, mutations in FDH have a deleterious effect on trichome differentiation. FDH transcripts were detected exclusively in the epidermis of young vegetative and floral organs. Plants overexpressing FDH under control of the cauliflower mosaic virus 35S promoter segregated fdh phenocopies, wild-type individuals, and plants showing severe retardation of growth and development. The dwarf plants displayed the most FDH expression, the fdh phenocopies generally the least. The protein product of FDH shows similarity to condensing enzymes involved in lipid biosynthesis, particularly those of the FATTY ACID ELONGATION family.
