Poster: Plant Pathogen/Symbiont Interactions

Abs # 706: IAA may regulate the potato response against fungal attack

Presenter:	Casalongue, Claudia , casalong@mdp.edu.ar
Authors	Casalongue, Claudia  (A)   Terrile, Cecilia  (A)   Olivieri, Florencia  (A)   Zanetti, Eugenia  (A)
Affiliations:	(A): Insituto de Investigaciones Biologicas

Auxins affect a great variety of cellular activities and are indispensable for the plant growth and development and they also participate in the responses against pathogen microorganisms. We reported the identification and characterization of a potato cDNA encoding an Aux/IAA protein, StIAA, isolated by a differential screening of a 24 h Fusarium eumartii infected potato tuber cDNA library. In order to investigate the possible role of auxin during potato-F. eumartii interaction, we also performed tubers bioassays. The IAA pretreatment prior to the fungus inoculation causes a decrease of 37% in the number of infected sites, respected to control tubers (mock solution plus F. eumartii). Moreover, the activity of an extracelular F. eumartii protease (FESP) associated with the pathogenicity was in vitro inhibited by intercellular washing fluids from IAA- pretreated potato tubers. Contrary, such inhibition was not evidenced when protease was incubated with control extracts. In addition, the proteolytic activity of potato tubers pretreated with IAA and subsequently inoculated with F. eumartii decreased respect to the non-IAA treated tubers. Other similar results were obtained for the pectinolytic activity. The patterns of extracellular pectinolytic activity were different between infected and IAA-pretreated infected tubers. Taken together, these results suggest that IAA may play a role in the regulation of the potato response against fungal attack. However, future studies are necessary to clarify the real IAA and StIAA protein function in stress situation.