IDENTIFICATION OF A BENZYLADENINE DISACCHARIDE CONJUGATE PRODUCED DURING SHOOT ORGANOGENESIS IN PETUNIA LEAF EXPLANTS

Prior studies of benzyladenine (BA) metabolism in Petunia hybrida Vilm . leaf explants during shoot organogenesis revealed the presence of an abundant unidentified BA conjugate. The BA conjugate, compound C, mad e up to 39% of the total pool of BA conjugates in two Petunia lines an d was associated with an increased shoot organogenic response when com pared with a third Petunia line that did not produce any compound C. S tructural analysis of compound C utilizing fast atom bombardment mass spectrometry, two methods of carbohydrate analysis, ultraviolet absorp tion spectra, and Fourier transform infrared spectra identified it as a new cytokinin conjugate, -[O-gluco-pyranosyl-(1-->3)-ribofuranosyl]- purine. Based on our prior biological studies and the similarity of th is compound to related cytokinin conjugates, this disaccharide cytokin in conjugate may be part of the interconvertible pool of cytokinins ac tive in Petunia shoot organogenesis.