SPS — Cucumis sativus

Summary

CsSPS (CSA_5G602150) on cucumber chromosome 5 encodes a protein with both spermidine synthase activity and spermine synthase activity (EC 2.5.1.16), placing it in the eukaryotic spermidine/spermine synthase family. The gene is associated with polyamine biosynthesis, including spermidine and spermine anabolism, as well as sex determination, regulation of photosynthesis, photorespiration, chlorophyll fluorescence, ethylene anabolism, and adventitious root development. It is linked to traits such as photosynthetic rate, quantum yield, sugar content, jasmonic acid content, and responses to high temperature, oxidative stress, drought, and salt stress. Associations with disease tolerance, including resistance to Botrytis cinerea and Pseudomonas syringae, and nematode susceptibility have also been noted. The protein localises to the cytosol, nucleus, mitochondria, and plasma membrane. Related genes in other species connect the family to polyamine metabolism, heat stress tolerance, and saline-alkali stress resistance.