Abstract

Prohexadione, a gibberellin (GA) biosynthesis inhibitor, was applied in ethanol around the circumference at the midpoint of the previous year terminal shoot of dormant Pinus sylvestris seedlings. After cultivating the seedlings under environmental conditions favorable for growth for 10 weeks, longitudinal and cambial growth were measured, and the endogenous levels of GA(1), GA(3), GA(4), GA(9), and indole-3-acetic acid (IAA) were determined by combined gas chromatography-mass spectrometry, using deuterated GAs and [C-13(6)]IAA as internal standards. Prohexadione application inhibited elongation and xylem and phloem production in the current year terminal shoot and xylem production in the previous year terminal shoots. Concomitantly, in both ages of shoots the cambial region contents of GA(1), GA(3), and GA(4) were decreased, whereas the level of GA(9) was increased. However, the IAA content was not altered in the terminal bud on the current year terminal shoot or in the cambial region of the current year or previous year terminal shoots. The results provide additional evidence that: (1) GAs are involved in the regulation of cambial growth, as well as longitudinal growth, in Pinus sylvestris shoots; (2) they act directly, rather than indirectly, by altering the IAA level; and (3) the GA(9) --> GA(4) --> GA(1) pathway is a major route of GA biosynthesis in conifer species.

Published in

Journal of Plant Growth Regulation
1995, Volume: 14, number: 4, pages: 175-181
Publisher: SPRINGER VERLAG

SLU Authors

• Moritz, Thomas

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Oden, Per

  • Department of Silviculture, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Botany


Publication identifier

DOI: https://doi.org/10.1007/BF00204909

Permanent link to this page (URI)

https://res.slu.se/id/publ/42917