SPERMINE ACCUMULATION AND OXIDATION INCREASE Arabidopsis thaliana TOLERANCE TO P. viridiflava

MARÍA ELISA GONZÁLEZ, CRISTINA BORTOLOTTI, MIGUEL BLAZQUEZ, PEDRO CARRASCO, ANTONIO TIBURCIO, FERNANDO PIECKENSTAIN AND O A RUIZ.

Tucumán. Argentina

Congreso; XLV Reunión Anual SAIB; 2009

SAIB

SPERMINE ACCUMULATION AND OXIDATION INCREASES A. thaliana TOLERANCE TO P. viridiflavaGonzález ME1; Bortolotti C2; Blázquez MA3; Carrasco P4; Tiburcio AF2; Pieckenstain FL5; Ruiz OA11IIB-INTECh Argentina. 2LFB FFUB España. 3IVMCP UPV-CSIC España. 4DBBM UV España. 5CIC Argentina. E-mail: mariaelisa@intech.gov.arApoplastic polyamine oxidation was previously found by our group to play a role in the defense of tobacco plants against necrotrophic and biotrophic pathogens. In addition, A. thaliana plants that accumulate the tetraamine spermine by overexpression of a SPERMINE SYNTHASE gene (35S::SPM) are less susceptible to P. viridiflava than spermine synthase null mutants (spm1-1) and wild type plants (WT). The aim of this work was to determine whether spermine-mediated tolerance of A. thaliana to P. viridiflava depends on the oxidation of this tetraamine and which polyamineoxidase (PAO) isoform is involved in this response. Feeding spm1-1 and WT A. thaliana plants with spermine led to increased tolerance to P. viridiflava, reaching a similar level to that of 35S::SPM plants. On the other hand, supplementation with the PAO inhibitor SL11061 led to increased susceptibility to P. viridiflava in the three Arabidopsis lines. Susceptibility of A. thaliana pao4-1 and pao5-1 null mutants was similar to that of WT plants, while pao1-1 null mutant exhibited increased susceptibility. The results of this work suggest that spermine-mediated tolerance of A. thaliana to P. viridiflava is due to oxidation of this tetramine by PAOs and the PAO1 isoform seems to play a specific role in this defense response. The relevance of two other PAO isoforms not evaluated in the present work remains to be established.