title: The effect of light on the gibberellin metabolism and growth of Phaseolus coccineus seedlings.
abstract: Light inhibits the rate of stem elongation of Phaseolus coccineus L. seedlings. Gibberellin A4 (GA4), an endogenous component of Phaseolus seedlings (Bowen et al., Phytochem. 12, 2935-2941, 1973) promotes stem growth in the light but not in darkness. Dark-grown seedlings contain larger GA pools than light-grown plants. Apically applied [(3)H]GA4 in etiolated bolised more extensively in the light. The slower rate of metabolism of [(3)H]GA4 in etiolated seedlings is not a consequence of isotopic dilution by the endogenous GA4 pool or a lack of penetration of the labelled material. While it can be concluded that the capacity of seedlings to metabolise [(3)H]GA4 is greater in the light than in darkness, it does not necessarily follow that there is a more rapid rate of turnover of endogenous GA4 in light-grown tissues. The results are discussed in relation to the involvement of GAs in the inhibitory effects of ligh on stem elongation.
authors.affiliation: Department of Botany, The University, G12 8QQ, Glasgow, U.K..
authors.forename: A W
authors.initials: AW
authors.lastname: Bown
authors.forename: D R
authors.initials: DR
authors.lastname: Reeve
authors.forename: A
authors.initials: A
authors.lastname: Crozier