title: Effect of brassinolide on gene expression in elongating soybean epicotyls.
abstract: We have studied the effect of brassinolide (BR), a plant steroidal lactone, on the expression of auxin-regulated genes in soybean (Glycine max L. cv Williams 82) epicotyls. BR caused up to 4-fold increases in epicotyl length during extended assays at 10(-7)m, in the absence of added auxin. Structurally related steroids failed to induce elongation or to alter the BR effect. Northern blot analysis, using sequences corresponding to auxin-regulated genes as probes, has shown that the molecular mechanism of BR-induced elongation is likely to differ from that of auxin-induced elongation in this system. BR does not rapidly induce members of the GH, SAUR, or JCW auxin-inducible gene families before the onset of elongation. BR enhances SAUR and GH1 transcripts after 18 h but has no effect on JCW1 or GH3 transcripts at any time examined. We have shown by two-dimensional gel analysis of in vitro translated mRNA that a submicromolar concentration of BR alters the pattern of gene expression in elongating soybean epicotyls.
authors.affiliation: Department of Biology, San Diego State University, San Diego, California 92182.
authors.forename: S D
authors.initials: SD
authors.lastname: Clouse
authors.forename: D M
authors.initials: DM
authors.lastname: Zurek
authors.forename: T C
authors.initials: TC
authors.lastname: McMorris
authors.forename: M E
authors.initials: ME
authors.lastname: Baker