Fructan Mobilization and the Involvement of Two β-Fructofuranosidases in Lycoris radiata Sprouting

Abstract

Seasonal changes of oligofructans, sucrose, glucose, and fructose contents in the various tissues of Lycoris radiata were followed by HPLC analyses. Oligofructans were found in all tissues except the scape, where large and nearly equal amounts of glucose and fructose were present. At the sprouting stage, oligofructans in the bulb greatly decreased with increases of both fructose content and β-fructofuranosidase activity. The bulb enzyme responsible for the fructan breakdown was a fructan exohydrolase that was inactive against sucrose, and the scape tissue contained a β-fructofuranosidase (EC 3.2.2.26) highly active toward sucrose. These results show a role of the accumulated fructans as an energy source for sprouting of the scape during the non-photosynthetic stage, the energy probably being supplied as sucrose.