Genome-Wide Characterization of the WOX Gene Family and Functional Analysis of ZoWOX6 Under Salt Stress in Zingiber officinale Roscoe

The WUSCHEL-related homeobox (WOX) transcription factor family comprises plant-specific regulators essential for meristem maintenance, organogenesis and abiotic stress adaptation. Ginger (Zingiber officinale Roscoe) is an economically important crop, whereas genome-wide characterization and functional analysis of its WOX family remain limited. Here, eight ZoWOX genes across the ginger genome were identified, which distributed on seven chromosomes and clustered into three clades. Promoter analysis revealed cis-acting elements, including stress- and hormone-responsive motifs. RNA-Seq and RT-qPCR revealed that the transcript level of ZoWOX6 was repressed under salt stress. Virus-induced gene silencing of ZoWOX6 improved salt tolerance, with 21.46% lower O2·− and 37.60% lower MDA content, 1.29-fold proline content, and 1.25, 1.12, and 1.20-fold SOD, POD, and CAT activities than controls under salt stress, respectively. Conversely, ZoWOX6 overexpression reduced salt resistance, resulting in 1.44-fold O2.− accumulation and 1.21-fold MDA content. Meanwhile, overexpression plants exhibited a 15.84% reduction in proline content, accompanied by decreased SOD, POD, and CAT activities by 15.55%, 10.42%, and 19.16%, respectively. In addition, the transcript levels of antioxidant-related genes, including ZoSOD1, ZoSOD2, ZoPOD1, ZoPOD2, ZoCAT1, and ZoCAT2, were significantly decreased by 14.68%, 29.68%, 36.55%, 21.08%, 33.76%, and 30.07%, respectively. These results indicate that ZoWOX6 acts as a negative regulator of salt stress response in ginger, and its salt-induced downregulation may alleviate growth inhibition and activate downstream defense pathways. This study provides a promising negative regulatory target for molecular breeding of stress-resistant ginger.