SlSWEET11b mediates sugar reallocation to regulate tomato stem morphogenesis

The regulation mechanism of stem development has been classified in both Arabidopsis and woody species. However, studies on the regulation of stem development in tomatoes are limited. SlSWEET11b, a plasma membrane-located sugar transporter with the ability to shuttle sucrose and hexose, is expressed in the stem, leaves, flower, and fruit. It showed stable high expression levels during tomato stem development. Overexpression of SlSWEET11b caused alter in sugar transport and accumulation in stem, together with the increase in stem diameter, xylem width and the xylem cell layers. Nonetheless, stem diameter and xylem width decreased when loss of SlSWEET11b. SlSWEET11b overexpression led to increased lignin concentration in the stems. Our results suggest that SlSWEET11b might mediate sugar relocation and regulate lignin biosynthesis during stem development, thereby affecting fruit yield and quality.