Spermine accumulation and oxidation increase A. thaliana tolerance to P. viridiflava

GONZALEZ, ME; BORTOLOTTI, C; BLÁZQUEZ, MA; CARRASCO, P; TIBURCIO, A; PIECKENSTAIN, FL; RUIZ, OA

San Miguel de Tucumán, Tucumán, Argentina

Congreso; XLV Reunión anual Sociedad argentina de investigación en bioquímica y biología molecular; 2009

Sociedad argentina de investigación en bioquímica y biología molecular

Apoplastic 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 whichpolyamineoxidase (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.