Abstract: 【Objective】 The study aimed to clone the highly expressed osmotic stress response factor gene （MeHOS15） of cassava and analyze its expression pattern and prokaryotic expression， thereby providing theoretical references for investigating the regulatory roles of the gene in cassava growth， development， and immune response. 【Method】 Taking a cassava variety SC124 as the material， the MeHOS15 gene was cloned by PCR and subjected to bioinformatics analysis， and a phylogenetic tree was constructed based on HOS protein sequences from Arabidopsis thaliana and rice. The expression pattern of MeHOS15 under different stress treatments was determined by real-time fluorescence quantitative PCR. The subcellular localization of MeHOS15 protein was observed by constructing pEGAD-MeHOS15-GFP fusion expression vector. The MeHOS15 protein was induced and expressed using a prokaryotic expression system， and expression of the protein was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS-PAGE） and Wes-tern blotting. 【Result】 The MeHOS15 gene was successfully cloned from cassava leaves， with its coding sequence （CDS） of 1725 bp， encoding 574 amino acid， and the cloned gene exhibited a similarity of 99.65% compared with the reference sequence in the Phytozome database （accession number： Manes.12G109000）， with its relative protein molecular weight of 64.67 kD and a theoretical isoelectric point of 5.41； MeHOS15 was classified as a stable hydrophilic protein containing the typical conserved the WD40 domain of WD40 protein family. Phylogenetic analysis showed that the MeHOS15 protein had the closest genetic relationship with HOS15 from Arabidopsis thaliana， and they shared similar domain structures. Real-time fluorescence quantitative PCR analysis revealed that the relative expression of MeHOS15 gene exhibited a trend of first increasing and then decreasing under treatments with Xanthomonas axonopodis pv. manihotis （Xam）， salt （NaCl，200 μmol/L）， hydrogen peroxide （5% H₂O₂）， salicylic acid （SA， 50 μmol/L）， and abscisic acid （ABA， 50 μmol/L）. Subcellular localization assays demonstrated that the MeHOS15 protein was localized in the nucleus and cell membrane. SDS-PAGE and Western blotting results confirmed that the protein MeHOS15 was successfully expressed at 28 ℃. 【Conclusion】 MeHOS15 is a member of the WD40 gene family， and NaCl， ABA， H₂O₂， SA， and Xam stresses could induce high expression of the gene， predicting that the MeHOS15 gene is involved in regulating responses of cassava to biotic and abiotic stresses.