The ERF5-WOX4 transcription factor regulatory module controls mannan biosynthesis in the orchid Dendrobium officinale.

Plants produce mannans, which compose a class of polysaccharides with considerable potential for health-related applications. GDP-mannose pyrophosphorylase (GMP) plays a pivotal role in mannan biosynthesis by facilitating the formation of GDP-mannose. In this study, we identified the WUSCHEL (WUS)-related homeobox (WOX) transcription factor DoWOX4 as a candidate protein that interacts with the DoGMP1 promoter in Dendrobium officinale through yeast one-hybrid library screening. We demonstrated that DoWOX4 directly binds to the DoGMP1 promoter and activates its expression. DoWOX4 overexpression significantly enhanced mannan biosynthesis, whereas silencing DoWOX4 inhibited this process. Furthermore, we found that the ethylene response factor 5 (DoERF5) binds to the DoWOX4 promoter in vitro. Subsequent analyses revealed that DoERF5 negatively regulates DoWOX4 and mannan biosynthesis. This study deepens our understanding of the regulatory mechanisms governing mannan biosynthesis in plants and provides valuable genetic resources for plant bio-breeding initiatives.