Transcription factor required for sugar partitioning from leaves to anthers during male reproductive development. Required for the production of functional pollen grains. Binds to the promoter of the anther-specific sugar transporter MST8 and regulates its expression. Regulates the expression of genes involved in sugar partitioning in flower, such as the sugar transporter SUT3, the invertase INV4, the UDP-glucose pyrophosphorylase UGP2 and the starch synthase WAXY. Expressed in root vascular tissue, primordia of lateral roots, leaf collar, and veins of lemma, palea and pistil. During anther development, expressed in anther vacuolar tissue from stage 9 to stage 13. Induced by wounding. Reduced plant size, and reduced levels of sugars in anthers leading to defective anthers and male sterility when grown under short day (12 hours light) conditions (PubMed:20305120, PubMed:23256151). No male sterility phenotype when grown under long day (14 hours light) conditions (PubMed:23256151).