Uptake and metabolism of 6-benzyladenine in ventilated cultures of kiwifruit plants

Uptake and metabolism of 6-benzyladenine (BA) were studied in Actinidia del iciosa explants grown on ventilated liquid Murashige and Skoog medium, usin g cellulose plugs as explant support, after 0.5, 1, 2, 8, 16, and 24h, 15 a nd 35 days of exposure to 14.8 kBq of 8-[C-14] BA. Absorption of the BA is a rapid process and in the first half hour of culture 65% of the initial am ount had disappeared from the medium. Exogenous BA was transformed into 7-b eta-D-glucopyranosyl-BA, 9-beta-D-glucopyranosyl-BA, [9G]BA, 3-beta-D-gluco pyranosyl-BA, 9-beta-D-ribofuranosyl-BA, [9R]BA, adenine, adenosine, and 5' -monophosphate of [9R]BA, [9R-5'P]BA. During the first 8h BA levels in the culture medium decreased, being converted into the active forms [9R]BA and [9R-5'P]BA. The excess of BA absorbed was inactivated by glucosidation yiel ding [9G]BA. Ventilated cultures favoured metabolization of active forms in to inactive compounds and this could be related to the lack of hyperhydric shoots.