Abstract: Abstract：The experiment was carried out to study the effects of exogenous Spd on SAMs gene expression in cucumber（Cucumis sativus L.‘Jinchun 2’）seedlings under salt stress with solution culture. The results showed that expressions of SAMs were up-regulated at 3，6，12 h by salt stress，and then were down-regulated after 24 h compared with that at normal level. Compared to salt stress，expressions of SAMs were down-regulated at 3，6，12 h with spraying Spd，and then were closed to control level after 24 h. The results revealed that exogenous Spd could mediate cucumber SAMs gene expression differentially，may regulate the biosynthesis pathway of SAM to enhance salt tolerance of cucumber. Protein bioinformatics analysis showed that the SAMs protein were relatively stable and have multiple phosphorylation sites. Cysteine residue of the 89 amino acid bit and the conserved sequence of 246 to 255 bits of DAGLTGRKII may play an important role in the function for SAMs enzyme. Meanwhile，we also derived three-dimensional structure of SAMs protein.

Key words: cucumber, salt stress, spermidine, SAMs