RESUMEN

Plant WRKY transcription factors can function as either positive or negative regulators of plant basal disease resistance. Arabidopsis WRKY48 is induced by mechanical and/or osmotic stress due to infiltration and pathogen infection and, therefore, may play a role in plant defense responses. WRKY48 is localized to the nucleus, recognizes the TTGACC W-box sequence with a high affinity in vitro and functions in plant cells as a strong transcriptional activator. To determine the biological functions directly, we have isolated loss-of-function T-DNA insertion mutants and generated gain-of-function transgenic overexpression plants for WRKY48 in Arabidopsis. Growth of a virulent strain of the bacterial pathogen Pseudomonas syringae was decreased in the wrky48 T-DNA insertion mutants. The enhanced resistance of the loss-of-function mutants was associated with increased induction of salicylic acid-regulated PR1 by the bacterial pathogen. By contrast, transgenic WRKY48-overexpressing plants support enhanced growth of P. syringae and the enhanced susceptibility was associated with reduced expression of defense-related PR genes. These results suggest that WRKY48 is a negative regulator of PR gene expression and basal resistance to the bacterial pathogen P. syringae.

Asunto(s)

Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Unión al ADN/metabolismo , Regulación de la Expresión Génica de las Plantas , Enfermedades de las Plantas/microbiología , Pseudomonas syringae/patogenicidad , Transactivadores/metabolismo , Factores de Transcripción/metabolismo , Secuencia de Aminoácidos , Arabidopsis/efectos de los fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Secuencia de Bases , Sondas de ADN , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/genética , Cinética , Datos de Secuencia Molecular , Peso Molecular , Enfermedades de las Plantas/prevención & control , ARN de Planta/química , ARN de Planta/genética , ARN Ribosómico/química , ARN Ribosómico/genética , Ácido Salicílico/farmacología , Alineación de Secuencia , Homología de Secuencia de Ácido Nucleico , Transactivadores/genética , Factores de Transcripción/genética