Studies on [₁₄C]‐glucose metabolism during shoot bud induction in cultured cotyledon explants of Pinus radiata

Abstract

Bender, L., Joy IV, R. W. and Thorpe, T. A. 1987. Studies on [ 14 C]‐glucose metabolism during shoot bud induction in cultured cotyledon explants of Pinus radiala. Excised cotyledons of Pinus radiata D. Don, cultured under shoot‐forming (plus N 6 ‐benzyladenine) and elongating (minus N 6 ‐benzyladenine) conditions, were fed U‐[ 14 C]‐glucose for 3 h in the light followed by a 3 h chase period immediately after excision (day 0) and after 3 days of culture (day 3). The incorporation of l4 C into individual soluble metabolites as well as into protein was followed. No labelled citrate could be detected at day 0, however, a flow of 14 C from glucose to glutamate/ glutamine occurred. During this stage the synthesis of glutamine strongly increased in the cotyledons supplied with N 6 ‐benzyladenine, which suggests a positive influence of this cytokinin on nitrogen incorporation prior to differentiation. After 3 days of cultivation large amounts of labelled citrate were detected. An increased incorporation of label into protein due to the cytokinin treatment was not detected during the early culture period (days 0 and 3). Labelled amino acids were incorporated into protein to different degrees, but this was not influenced by the hormonal treatment.