Sucrose is loaded into the phloem in the minor veins of leaves before export. Two active, species-specific loading mechanisms have been proposed. One involves transporter-mediated sucrose transfer from the apoplast into the sieve element-companion cell complex, so-called apoplastic loading. In the
Galactan:galactan galactosyltransferase (GGT) is a unique enzyme of the raffinose family oligosaccharide (RFO) biosynthetic pathway. It catalyzes the chain elongation of RFOs without using galactinol (alpha-galactosyl-myoinositol) by simply transferring a terminal alpha-galactosyl residue from one