Seagrass meadows are among the four most productive marine natural ecosystems in the world. Zostera japonica (Z. japonica) is the most widely distributed species of seagrass in China. Nucleotide exchange factors (NEFs) promote the release of ADP during heat stress, accelerating the rate-limiting step of Heat shock protein 70 (Hsp70). Although NEFs play an important role in abiotic stress tolerance of plants, NEFs in seagrass have not been studied. In this study, we cloned Fes1 from Z. japonica (ZjFes1) by rapid amplification of the cDNA ends using RACE, and full length ZjFes1 was 1171 bp. It contained an 81 bp 5'-terminal untranslated region (UTR), 109 bp 3'-UTR and 981 bp open reading frame (ORF). The ORF (ZjFes1) was predicted to encode a polypeptide of 326 amino acids with theoretical molecular weight (MW) of 36.10 kDa and pI of 5.22. ZjFes1 shared 89% amino acid identity with Fes1 from Zostera marina (Z. marina). The transcriptional levels of ZjFes1 increased significantly 1 h after heat treatment. ZjFes1 was localized to the cytoplasm. Taken together, we found that ZjFes1 was a stress-inducible gene that may be involved in heat stress response. This study lays the foundation for further studies on the role of ZjFes1 in heat resistance.
Keywords: Heat stress; Nucleotide exchange factor; Seagrasses; Z. japonica.