MODULATION OF POLYAMINE METABOLISM BY SALICYLIC ACID IN Arabidopsis thaliana AND Nicotiana tabacum

ROSSI FR.; MARINA M; ROMERO FM; GARRIZ A; RUIZ OA; PIECKENSTAIN FL.

San Miguel de Tucuman - Tucuman

Congreso; Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular; 2009

Polyamines (PAs) are natural aliphatic polycations with multiple functions. Although plant PA metabolism is affected by pathogen attack, the signalling events involved in the regulation of PA metabolism during plant infection are not well known. In this work, the role of salicylic acid (SA) in the regulation of PA levels and the expression of genes involved in PA metabolism was investigated in the model plants Arabidopsis thaliana and Nicotiana tabacum. PA levels were modified when Arabidopsis plants were supplied with SA. Putrescine levels were higher in treated plants than in controls, as opposed to spermidine and spermine, both of which decreased in response to SA. The levels of arginine decarboxylase 2 and spermine synthase transcripts were higher in SA-supplied plants than in controls. Moreover, some modifications were observed in transcript levels of genes coding for enzymes involved in PA catabolism. Thus, transcripts of polyamine oxidase 4, an enzyme that oxidizes spermidine and spermine to produce putrescine, were significantly increased by SA treatment. PA levels and arginine decarboxylase transcripts of tobacco plants were increased by SA treatment. A high dose (200 μM) of SA induced the accumulation of the PA oxidation product 1,3-diaminopropane. As a whole, these observations show that SA, a key regulator of plant responses to biotic stress, modulates PA metabolism.