A novel phytoene synthase paralog from halophytic Salicornia confers salinity tolerance in plants

Salicornia seems to be a suitable euhalophyte for the study of salt stress resilience mechanism and exploitation of salinity-tolerant genes for crop yield improvement. In this study, we cloned a novel SePSY1 gene from an extremely salt-tolerant glycophyte, Salicornia europaea. The sequence analysis revealed that the newly isolated gene is a paralog of PSY, suggesting a gene duplication event in Salicornia. The newly isolated gene encodes a protein of 419 amino acids. The C-terminus containing a Trans-IPPS-H domain with catalytic and binding regions exhibits considerable conservation in various species, while the N-terminus remained divergent. The structural analysis suggested a catalytic role of the C-terminus in the first step of carotenoid biosynthesis, whereas N-terminus is involved in the transport and localization of protein. Gene expression using real-time RT-PCR revealed enhanced transcript signals for salt-treated plants. Transgenic Arabidopsis plants overexpressing SePSY1 could withstand 200 mM salt stress in comparison with the wild-type counterpart. Thus, SePSY1 confers salinity stress tolerance in the heterologous system. Strength of gene expression is positively correlated with severity of phenotypes. Our results reveal that the SePSY1 gene can be a potential target for improving salinity tolerance in crop plants that are susceptible to this stress.