Characterization of Stilbene Synthase Genes in Mulberry (<i>Morus atropurpurea</i>) and Metabolic Engineering for the Production of Resveratrol in <i>Escherichia coli</i>

Stilbenes have been recognized for their beneficial physiological effects on human health. Stilbene synthase (STS) is the key enzyme of resveratrol biosynthesis and has been studied in numerous plants. Here, four <i>MaSTS</i> genes were isolated and identified in mulberry (<i>Morus atropurpurea</i> Roxb.). The expression levels of <i>MaSTS</i> genes and the accumulation of <i>trans</i>-resveratrol, <i>trans</i>-oxyresveratrol, and <i>trans</i>-mulberroside A were investigated in different plant organs. A novel coexpression system that harbored 4-coumarate:CoA ligase gene (<i>Ma4CL</i>) and <i>MaSTS</i> was established. Stress tests suggested that <i>MaSTS</i> genes participate in responses to salicylic acid, abscisic acid, wounding, and NaCl stresses. Additionally, overexpressed <i>MaSTS</i> in transgenic tobacco elevated the <i>trans</i>-resveratrol level and increased tolerance to drought and salinity stresses. These results revealed the major <i>MaSTS</i> gene, and we evaluated its function in mulberry, laying the foundation for future research on stilbene metabolic pathways in mulberry