Role of Arginine Decarboxylase (ADC) in Arabidopsis thaliana defence against the pathogenic bacterium Pseudomonas viridiflava

ROSSI, FRANCO RUBÉN; MARINA, MARÍA; PIECKENSTAIN, FERNANDO LUIS

PLANT BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015 vol. 16 p. 831 - 839

1435-8603

Polyamines are involved in plant responses to environmental stimuli and pathogen attack. Polyamine biosynthesis starts with the production of putrescine through the decarboxylation of arginine or ornithine. In Arabidopsis thaliana, putrescine is synthesized by arginine decarboxylase (ADC), while the ornithine decarboxylase pathway is absent. Arabidopsis harbors two ADC isoforms (ADC1 and 2) that are differentially regulated by diverse abiotic stimuli, but their role in defence against pathogens has not been studied in depth. This work analysed the participation of ADC in Arabidopsis defence against Pseudomonas viridiflava infection. ADC activity and expression, polyamine levels and bacterial resistance were analysed in null mutants of each ADC isoform and WT plants. In non-infected WT plants, ADC2 expression was much higher than ADC1. Analysis of adc mutants demonstrated that ADC2 contributes in a much higher extent than ADC1 to basal ADC activity and putrescine biosynthesis. Bacterial infection induced putrescine accumulation and ADC1 expression in WT plants. Moreover, putrescine accumulation in response to infection was blocked in adc1 mutants. These results suggest a specific participation of ADC1 in defence, although basal resistance was not decreased by dysfunction of any of the two ADC genes. In addition, and as opposed to WT plants, bacterial infection increased ADC2 expression and ADC activity in adc1 mutants, which could counterbalance the lack of ADC1 in this line. Results demonstrate the specific induction of ADC1 in response to bacterial infection and a certain degree of functional redundancy between both isoforms in relation to their contribution to basal resistance.