Vacuolar sugar transporter OsERD5 increases rice tillering and yield by modulating intracellular hexose homeostasis

The early responsive to dehydration-like (ERDL or ERD) subfamily, subclade within the monosaccharide transporter (MST) superfamily, is crucial in the regulation of growth and seed yield in Arabidopsis. Here, we identified OsERD5 as an AtERDL6 homologue and explored the function of OsERD5 . We found that OsERD5 overexpression significantly enhanced the tiller number and grain yield of rice. OsERD5 was widely expressed in aboveground tissues, encoded a tonoplast-localized protein, and exhibited transport activities for fructose, glucose and mannose when expressed in yeast. Expression character assay revealed that OsERD5 mediated hexose efflux across tonoplasts and participated in maintaining the diurnal rhythm-regulated intracellular hexose homeostasis. Additional physiological and molecular evidence showed that OsERD5 overexpression promoted vacuolar glucose efflux, enhanced sucrose synthesis and transport, increased sugar content in the shoot base, and promoted rice tillering by activating the synthesis of cytokinin simultaneously repressing strigolactone and gibberellin signaling. This study elucidates the function of OsERD5 and the mechanism underlying the overexpression of OsERD5 increasing rice tillering and yield.