Soluble sugar component-based quality assessment and SWEET transport family identification uncovering soluble sugar accumulation mechanism in Zostera marina

Zostera marina L. is a marine medicinal plant with important ecological functions and considerable medicinal value. However, the absence of a systematic quality evaluation system has limited the development and utilization of its medicinal resources. In addition, the molecular basis of soluble sugar accumulation and transport in Zostera marina remains poorly understood. In this study, four Zosteraceae species were collected, and the contents of 11 soluble sugar components were determined. A quality evaluation system based on soluble sugar components was established using chemometric methods. Furthermore, based on the genomic data of Zostera marina , members of the SWEET gene family were systematically identified and analyzed for their physicochemical properties, subcellular localization, transmembrane domains, conserved motifs, gene structures, and cis-acting regulatory elements. The transport activity of selected ZosmaSWEET proteins was further verified in yeast. The results showed that Zostera marina had clear advantages in the contents of glucose, fructose, and several other soluble sugar components, indicating that it represents a high-quality medicinal germplasm resource. A total of eight ZosmaSWEET genes were identified in Zostera marina . Most of the encoded proteins were predicted to localize to the plasma membrane and contained typical transmembrane domains, conserved motifs, and domain architectures. Cis-acting element analysis suggested that the expression of these genes is mainly regulated by light signals and hormones. Among them, ZosmaSWEET8 exhibited glucose transport activity in yeast. This study established a soluble sugar component-based quality evaluation system for Zosteraceae species and systematically elucidated the structural and functional characteristics of the SWEET gene family in Zostera marina for the first time. These findings provide theoretical and technical support for the development, quality control, and molecular breeding of marine medicinal plant resources.