biologia plantarum

Biologia plantarum 54:677-683, 2010 | DOI: 10.1007/s10535-010-0120-1

Salicylic acid increased aldose reductase activity and sorbitol accumulation in tomato plants under salt stress

I. Tari^1,*, G. Kiss², A. K. Deér², J. Csiszár¹, L. Erdei¹, Á. Gallé¹, K. Gémes¹, F. Horváth¹, P. Poór¹, Á. Szepesi¹, L. M. Simon²

¹ Department of Plant Biology, University of Szeged, Szeged, Hungary

² Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary

Increased aldose reductase (ALR) activities were detected in the leaf tissues of tomato plants grown for 3 weeks in culture medium containing 10^-7 or 10^-4 M salicylic acid (SA), and in the roots after the 10^-4 M SA pretreatment. The ALR activity changed in parallel with the sorbitol content in the leaves of the SA-treated plants. Salt stress elicited by 100 mM NaCl enhanced the accumulation of sorbitol in the leaves of control plants and as compared with the untreated control the sorbitol content in the SA-pretreated leaves remained elevated under salt stress. DEAE cellulose anionexchange column purification of the protein precipitated with 80 % (NH₄)₂SO₄ revealed two enzyme fractions with ALR activity in both the leaf and the root tissues. The fraction of the leaf extract that was not bound to the column reacted with glucose and glucose-6-P as substrates, whereas glucose was not a substrate for the bound fraction or for root isoenzymes. The root enzyme was less sensitive to salt treatment: 50 mM NaCl caused 30 % inhibition in the leaf extract, whereas the enzyme activity of the root extract was not affected. It is suggested that increased ALR activity and sorbitol synthesis in the leaves of SA-treated tomato plants may result in an improved salt stress tolerance.

Keywords: alterations of ALR activity in vitro; enzyme purification; Lycopersicon esculentum; NaCl

Subjects: Lycopersicon esculentum

Received: January 25, 2009; Accepted: October 17, 2009; Published: December 1, 2010  Show citation