Defoliation induces fructan 1-exohydrolase II in witloof chicory roots. Cloning and purification of two isoforms, fructan 1-exohydrolase IIa and fructan 1-exohydrolase IIb. Mass fingerprint of the fructan 1-exohydrolase II enzymes
The cloning of two highly homologous chicory (Cichorium intybus var, foliosum cv mash) fructan 1-exohydrolase cDNAs (1-FEH IIa and 1-FEH IIb) is described. Both isoenzymes could be purified from forced chicory roots as well as from the etiolated "Belgian endive" leaves where the 1-FEH IIa isoform is present in higher concentrations. Full-length cDNAs were obtained by a combination of reverse transcriptase-polymerase chain reaction (PCR), PCR and 5 '- and 3 ' -rapid amplification of cDNA ends using primers based on N-terminal and conserved amino acid sequences. 1-FEH IIa and 1-FEH IIb cDNA-derived amino acid sequences are most homologous to a new group of plant glycosyl hydrolases harboring cell wall-type enzymes with acid isoelectric points. Unlike the observed expression profiles of chicory I-FEH I, northern analysis revealed that 1-FEH II is expressed when young chicory plants are defoliated, suggesting that this enzyme can be induced at any developmental stage when large energy supplies are necessary (regrowth after defoliation).