University of Tasmania
Browse

The brassinosteroid growth response in pea is not mediated by changes in gibberellin content

Download (381 kB)
journal contribution
posted on 2023-05-16, 17:04 authored by Jager, C, Symons, GM, John RossJohn Ross, Jennifer SmithJennifer Smith, James ReidJames Reid
The objective of this study was to increase our understanding of the relationship between brassinosteroids (BRs) and gibberellins (GAs) by examining the effects of BR deficiency on the GA biosynthesis pathway in several tissue types of pea (Pisum sativum L.). It was suggested recently that, in Arabidopsis, BRs act as positive regulators of GA 20-oxidation, a key step in GA biosynthesis [Bouquin et al. (2001) Plant Physiol 127:450-458]. However, this may not be the case in pea as GA20 levels were consistently higher in all shoot tissues of BR-deficient (lk and lkb) and BR-response (lka) mutants. The application of brassinolide (BL) to lkb plants reduced GA20 levels, and metabolism studies revealed a reduced conversion of GA19 to GA20 in epi-BL-treated lkb plants. These results indicate that BRs actually negatively regulate GA20 levels in pea. Although GA 20 levels are affected by BR levels, this does not result in consistent changes in the level of the bioactive GA, GA1. Therefore, even though a clear interaction exists between endogenous BR levels and the level of GA20, this interaction may not be biologically significant. In addition to the effect of BRs on GA levels, the effect of altered GA 1 levels on endogenous BR levels was examined. There was no significant difference in BR levels between the GA mutants and the wild type (wt), indicating that altered GA1 levels have no effect on BR levels in pea. It appears that the BR growth response is not mediated by changes in bioactive GA levels, thus providing further evidence that BRs are important regulators of stem elongation. © Springer-Verlag 2004.

History

Publication title

Planta

Volume

221

Pagination

141-148

ISSN

0032-0935

Department/School

School of Natural Sciences

Publisher

Springer-Verlag

Place of publication

Germany

Repository Status

  • Restricted

Socio-economic Objectives

Environmentally sustainable plant production not elsewhere classified

Usage metrics

    University Of Tasmania

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC