Spatial distribution of fructans and fructan metabolizing enzymes in rhizophores of Vernonia herbacea (Vell.) Rusby (Asteraceae) in different developmental phases

The underground reserve organs of Vernonia herbacea, the rhizophores, are stems with positive geotropic growth, with the apex (distal region) presenting the younger tissues, and the sprouting of new shoots occurring by development of buds located on the opposing end of the rhizophore (proximal region). Fructan contents and the activities of enzymes related to fructan metabolism were analysed in plants in different developmental phases in the distal, median and proximal regions of the rhizophores. Data showed a spatial and temporal distribution of the activities of 1-SST, 1-FFT, invertase and 1-FEH, revealed mainly by high biosynthetic activity in the distal region of the rhizophore during the vegetative phase and by a high fructan mobilization activity in the proximal region of the rhizophores in plants at the sprouting phases. The differences in enzyme activities could not be clearly correlated with differences in fructan contents, due mostly to the high fructan concentrations present in the rhizophores.