Transferase involved in fructan biosynthesis that catalyzes the production of 1-kestose (fructose and nystose to a lower extent) from sucrose. Exhibits also some hydrolase activity toward 1-kestose, thus producing fructose and sucrose. A weak fructosyltransferase activity leads to the formation of nystose from 1-kestose. 2 sucrose = 1(F)-beta-D-fructosylsucrose + D-glucose Monomer. Accumulates at the base of growing leaves. Belongs to the glycosyl hydrolase 32 family.