Inhibition of growth of microcultured Hancornia speciosa shoots by 3beta-hydroxylated gibberellins and one of their C-3 deoxy precursors.
Gibberellins (GAs) A(1), A(3), A(4) and A(7), all 3beta-hydroxylated, growth-active GAs, significantly inhibited shoot elongation and the formation of nodes in in vitro-grown Hancornia speciosa, as did GA(20), a 3-deoxy precursor of GA(1). Ancymidol, an early-stage inhibitor of GA biosynthesis, significantly retarded shoot elongation without affecting the formation of nodes. Co-application of ancymidol and GA(1 )did not overcome the ancymidol-induced growth retardation. Trinexapac-ethyl, which can inhibit 3beta-hydroxylation (GA activation) and 2beta-hydroxylation (GA inactivation), gave no significant response on either shoot elongation or node formation, while two isomers of 16,17-dihydro GA(5), also inhibitors of GA 3beta-hydroxylation, significantly inhibited both shoot growth and the formation of nodes. These unusual results may indicate a unique metabolism for GAs in microcultured shoots of H. speciosa.
Pereira-Netto
A B
AB
Department of Botany-SCB, University of Parana, C.P. 19031, 81531-970, Curitiba, PR, Brazil. apereira@bio.ufpr.br
McCown
B H
BH
Pharis
R P
RP
D029062:Apocynaceae / Q000187:drug effects / Q000254:growth & development*; D046508:Culture Techniques; D004305:Dose-Response Relationship, Drug; D005875:Gibberellins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000494:pharmacology*; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development*; D011743:Pyrimidines / Q000494:pharmacology
D005875:Gibberellins; D011743:Pyrimidines; C053577:ancymidol