RESUMEN
Infected plants undergo transcriptional reprogramming during initiation of both local defence and systemic acquired resistance (SAR). We monitored gene-expression changes in Arabidopsis thaliana under 14 different SAR-inducing or SAR-repressing conditions using a DNA microarray representing approximately 25-30% of all A. thaliana genes. We derived groups of genes with common regulation patterns, or regulons. The regulon containing PR-1, a reliable marker gene for SAR in A. thaliana, contains known PR genes and novel genes likely to function during SAR and disease resistance. We identified a common promoter element in genes of this regulon that binds members of a plant-specific transcription factor family. Our results extend expression profiling to definition of regulatory networks and gene discovery in plants.
Asunto(s)
Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/microbiología , Análisis por Conglomerados , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Análisis de Secuencia por Matrices de Oligonucleótidos , Oomicetos/parasitología , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiología , Regiones Promotoras Genéticas , Regulón , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Transcripción GenéticaRESUMEN
The WRKY proteins are a superfamily of transcription factors with up to 100 representatives in Arabidopsis. Family members appear to be involved in the regulation of various physio-logical programs that are unique to plants, including pathogen defense, senescence and trichome development. In spite of the strong conservation of their DNA-binding domain, the overall structures of WRKY proteins are highly divergent and can be categorized into distinct groups, which might reflect their different functions.
Asunto(s)
Proteínas de Plantas/metabolismo , Plantas/metabolismo , Factores de Transcripción/metabolismo , Secuencia de Aminoácidos , Datos de Secuencia Molecular , Proteínas de Plantas/química , Homología de Secuencia de Aminoácido , Factores de Transcripción/químicaRESUMEN
Parsley WRKY proteins comprise a family of plant-specific zinc-finger-type factors implicated in the regulation of genes associated with pathogen defence. In vitro, these proteins bind specifically to functionally defined TGAC-containing W box promoter elements within the Pathogenesis-Related Class10 (PR-10) genes. Here we present in vivo data demonstrating that WRKY1 is a transcriptional activator mediating fungal elicitor-induced gene expression by binding to W box elements. In situ RNA hybridization revealed that the WRKY1 gene is rapidly and locally activated in parsley leaf tissue around fungal infection sites. Transient expression studies in parsley protoplasts showed that a specific arrangement of W box elements in the WRKY1 promoter itself is necessary and sufficient for early activation and that WRKY1 binds to such elements. Our results demonstrate that WRKY transcription factors play an important role in the regulation of early defence-response genes including regulation of WRKY1.