VvSWEET10 Mediates Sugar Accumulation in Grapes

Abstract

Sugar accumulation is a critical event during grape berry ripening that determines the grape market values. Berry cells are highly dependent on sugar transporters to mediate cross-membrane transport. However, the role of sugar transporters in improving sugar accumulation in berries is not well established in grapes. Herein we report that a Sugars Will Eventually be Exported Transporter (SWEET), that is, VvSWEET10, was strongly expressed at the onset of ripening (véraison) and can improve grape sugar content. <i>VvSWEET10</i> encodes a plasma membrane-localized transporter, and the heterologous expression of <i>VvSWEET10</i> indicates that <i>VvSWEET10</i> is a hexose-affinity transporter and has a broad spectrum of sugar transport functions. <i>VvSWEET10</i> overexpression in grapevine calli and tomatoes increased the glucose, fructose, and total sugar levels significantly. The RNA sequencing results of grapevine transgenic calli showed that many sugar transporter genes and invertase genes were upregulated and suggest that <i>VvSWEET10</i> may mediate sugar accumulation. These findings elucidated the role of <i>VvSWEET10</i> in sugar accumulation and will be beneficial for the improvement of grape berry quality in the future.