Spermine accumulation under salt stress

MAIALE SANTIAGO; GUIRADO ALEJANDRA; SÁNCHEZ DIEGO; VIDAL ALFONSO; RUIZ OSCAR

JOURNAL OF PLANT PHYSIOLOGY

ELSEVIER GMBH

Año: 2004 vol. 161 p. 35 - 42

0176-1617

Polyamines have long been recognized to be linked to stress situations, and it is generally acceptedthat they have protective characteristics. However, little is known about their physiological relevancein plants subjected to long-term salt stress. In order to precise their importance, two rice (Oryza sat-iva) cultivars differing in their salt tolerance were salinized for 7, 14 and 21 days. The activities ofsome of the enzymes involved in polyamine metabolism, free polyamines and proline contents wereevaluated. Arginine decarboxylase and S-adenosyl-L-methionine decarboxylase activities werereduced in both cultivars as a consequence of salt treatment. However, spermidine synthase activitywas reduced in the salt tolerant cultivar (var Giza) but not in the salt sensitive (var El Paso), while nopolyamine oxidase activity was detected. During the salinization period, putrescine and spermidinelevels decreased in both cultivars, although less dramatically in Giza. Simultaneously, spermineaccumulations occur in both varieties, while proline accumulation was major in the sensitive one.However, spermine accumulation induced by treatment with spermidine synthase inhibitor cyclohe-xylamine, determined no reduction in leaf injury associated with salt stress in both cultivars. The datapresented suggest that spermine accumulation is not a salt tolerance trait.