WUSCHEL-related homeobox (WOX) transcription factors are plant-specific members that characterized by the presence of a homeodomain. it has been shown that WoX members regulate several aspects of plant development, but the biological functions of this CsWOX gene family remain largely unknown in cucumber (Cucumis sativus L.). In this study, we identified and characterized 11 putative CsWOX genes in cucumber, which are also divided into three major clades (e.g., the Ancient clade, the Intermediate clade and the WUS clade). Expression pattern analysis revealed tissue-specific expression patterns of CsWOX genes, including that CsWOX9 is mainly expressed in developing fruit and also has lower expression in tip and axillary bud, which was further confirmed by in situ hybridization assay. Moreover, overexpression of CsWOX9 in Arabidopsis led to increased branches and rosette leaves, and shorter siliques. together, these results indicated that csWoX members may regulate cucumber growth and development. WUSCHEL-related homeobox (WOX) gene family are plant-specific transcription factors, which belong to homeobox superfamily. All WOX members contain a homeodomain with 60-66 amino acid residues. According to evolutionary relationships, they can be divided into WUS, Intermediate and Ancient clades 1-3. These WOX members have been identified and studied in many species including Arabidopsis, rice, maize and soybean. So far, it has been found that WOX transcription factors play important roles in regulating many aspects of growth and development including meristematic stem cell maintenance, embryonic development and polarization, lateral organ development, and organ regeneration. The founding member AtWUS is expressed in stem apical meristem (SAM) and is necessary for SAM formation and maintenance 2,4-6. In addition to AtWUS, other WOX members are also involved in stem cell maintenance. For example, AtWOX5 is enriched in the quiescent center and plays an important role in maintaining the stability of stem cells of root apical meristem, similar to AtWUS in SAM 7. WOX4 is mainly expressed in the procambium and cambium, and promotes differentiation and/or maintenance of the vascular procambium in Arabidopsis and tomato 8,9. WOX9 promotes the growth of SAM and is required for the maintenance of WUS expression at the shoot apex, and mediates cytokinin signaling during shoot meristem establishment 10. The involvement of WOX members in plant development is not limited to stem cell maintenance. For example, AtWOX2 contributes to early pre-embryo and cotyledon boundary formation during embryo development in the egg cell and zygote 11. Consistently, PaWOX2 also likely regulates embryo cell division and/or differentiation in Picea abies 12. AtWOX7 is expressed at all stages of lateral root development, and inhibits lateral root development in a sugar-dependent manner 13. Similarly, OsWOX6 and OsWOX11 are expressed asymmetrically in response to auxin control rice tiller angle 14. Moreover, AtWOX11 and AtWOX12 play important roles in de nov...