FRUCTAN OLIGOMERS IN POA AMPLA

Ion exchange chromatography of water extracts was used to classify the fructans in leaves of 40 temperate dicots and 110 temperate grass spe cies. Of the 150 species studied, only Poa ampla (Merrill) contained a single beta-2,6 linked fructan series. All other species grown at 10/ 5 degrees C day/night temperatures (16 h dap) contained some beta-1,2 linked oligofructans, even when the major fructan series was beta-2,6 linked. Leaves of P. arnpba plants grown at 15/10 degrees C day/night temperatures contained some beta-1,2 linked fructans and raffinose in addition to the dominant beta-2,6 series, but did not contain signific ant amounts of 1-kestose or bifurcose (1&6-kestotetraose). Leaves of P oa arctica R.Br. and Poa bulbosa L. contained significant amounts of r affinose and various beta-1,2 linked oligomers but no 1-kestose. In vi vo synthesis of 6-kestose in leaves of P. ampla grown at 10/5 degrees C proceeds in the absence of significant amounts of either 1-kestose o r bifurcose. Thus P. ampla probably has a specific 6-SST (6-sucrose-su crosefructosyl transferase) and might provide a ready source of beta-2 ,6 linked grass fructan.