Abstract

Pathogenesis-related (PR) proteins are involved in plant defense and have multiple functional adaptations that assist in resisting various pathogens and tolerating environmental stress. Salix matsudana Koidz, a deciduous, rapidly growing willow species, can tolerate a range of adverse conditions. Comparative proteomic analysis previously revealed that the S. matsudana PR protein SmPR10 was abundant and up-regulated with 100   mM NaCl treatment. In this study, the SmPR10 gene from S. matsudana was cloned and characterized to determine its role in salt tolerance. The amino acid sequence of SmPR10 showed 98% and 93% sequence homology with PR proteins from S. purpurea and Populus trichocarpa , respectively. SmPR10 was localized in the cytoplasm of Arabidopsis protoplasts. SmPR10 transcript and protein levels were high in roots, and its expression was up-regulated in roots treated with 100   mM NaCl. SmPR10 was detected specifically in phloem fiber cells and root xylem by immunolocalization analysis. Moreover, heterogeneous overexpression of SmPR10 enhanced the salt tolerance of transgenic Arabidopsis plants as shown by analysis of root length, root number, and Na + flux, as well as physiological parameters such as chlorophyll content, MDA content, electrical conductivity, and SOD and POD enzyme activity levels. Our results reveal that SmPR10 plays an important role in salt tolerance and could serve as an important candidate gene to improve salt tolerance in woody species through genetic engineering.