Evidence for a positive regulatory role of strawberry (Fragaria x ananassa) Fa WRKY1 and Arabidopsis At WRKY75 proteins in resistance.
Knowledge of the molecular basis of plant resistance to pathogens in species other than Arabidopsis is limited. The function of Fa WRKY1, the first WRKY gene isolated from strawberry (Fragaria x ananassa), an important agronomical fruit crop, has been investigated here. Fa WRKY1 encodes a IIc WRKY transcription factor and is up-regulated in strawberry following Colletotrichum acutatum infection, treatments with elicitors, and wounding. Its Arabidopsis sequence homologue, At WRKY75, has been described as playing a role in regulating phosphate starvation responses. However, using T-DNA insertion mutants, a role for the At WRKY75 and Fa WRKY1 in the activation of basal and R-mediated resistance in Arabidopsis is demonstrated. At wrky75 mutants are more susceptible to virulent and avirulent isolates of Pseudomonas syringae. Overexpression of Fa WRKY1 in At wrky75 mutant and wild type reverts the enhanced susceptible phenotype of the mutant, and even increases resistance to avirulent strains of P. syringae. The resistance phenotype is uncoupled to PATHOGENESIS-RELATED (PR) gene expression, but it is associated with a strong oxidative burst and glutathione-S-transferase (GST) induction. Taken together, these results indicate that At WRKY75 and Fa WRKY1 act as positive regulators of defence during compatible and incompatible interactions in Arabidopsis and, very likely, Fa WRKY1 is an important element mediating defence responses to C. acutatum in strawberry. Moreover, these results provide evidence that Arabidopsis can be a useful model for functional studies in Rosacea species like strawberry.
Encinas-Villarejo
Sonia
S
Departamento de Bioquímica y Biología Molecular e Instituto Andaluz de Biotecnología, Campus de Rabanales, Edificio Severo Ochoa (C-6), Universidad de Córdoba, E-14071 Córdoba, Spain.
Maldonado
Ana M
AM
Amil-Ruiz
Francisco
F
de los Santos
Berta
B
Romero
Fernando
F
Pliego-Alfaro
Fernando
F
Muñoz-Blanco
Juan
J
Caballero
José L
JL
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D031985:Fragaria / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D007113:Immunity, Innate; D008969:Molecular Sequence Data; D020081:Phyllachorales / Q000502:physiology; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D044224:Pseudomonas syringae / Q000472:pathogenicity / Q000502:physiology; D016415:Sequence Alignment; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D014774:Virulence
D029681:Arabidopsis Proteins; D010940:Plant Proteins; D014157:Transcription Factors; C544317:WRKY75 protein, Arabidopsis