Ontogenetic variation in levels of gibberellin A1inPisum

✍ Scribed by John J. Ross; James B. Reid; Heidi S. Dungey

• Publisher: Springer-Verlag
• Year: 1992
• Tongue: English
• Weight: 548 KB
• Volume: 186
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00196245

✦ Synopsis

The levels of the biologically active gibberellin (GA), GA1, and of its precursor, GA20, were monitored at several stages during ontogeny in the apical portions of isogenic tall (Le) and dwarf (le) peas (Pisum sativum L.) using deuterated internal standards and gas chromatography-selected ion monitoring. The levels of both GAs were relatively low on emergence and on impending apical arrest. At these early and late stages of development the internodes were substantially shorter than at intermediate stages, but were capable of large responses to applied GA 3. Tall plants generally contained 10-18 times more GA 1 and possessed internodes 2-3 times longer than dwarf plants. Further, dwarf plants contained 3-5 times more GA20 than tall plants. No conclusive evidence for the presence of GA3 or GA 5 could be obtained, even with the aid of [2H2]GA 3 and [2H2]GA 5 internal standards. If GA3 and GA s were present in tall plants, their levels were less than 0.5% and 1.4% of the level of GA1, respectively. Comparison of the effects of gene le on GA1 levels and internode length with the effects of ontogeny on these variables shows that the ontogenetic variation in GA 1 content was sufficient to account for much of the observed variation in internode length within the wild-type. However, evidence was also obtained for substantial differences in the potential length of different internodes even when saturating levels of exogenous GA3 were present.