Bacteria have evolved gibberellin phytohormone biosynthesis independently of plants and fungi. Through 13C-labeling and NMR analysis, the mechanistically unusual "B" ring contraction catalyzed by a cytochrome P450 (CYP114), which is the committed step in gibberellin biosynthesis, was shown to occur via oxidative extrusion of carbon-7 from ent-kaurenoic acid in bacteria. This is identical to the...

Gibberellic acid induced growth in Avena (oat) stem segments within 35 minutes after hormone application. The total elongation elicited by gibberellic acid was greater than 15 times the control growth. The sensitivity of the segments to low concentrations of gibberellic acid (1 pmole) and the specificity of the segments to the gibberellin class of hormones suggest that oat stem segments would b...

Gibberellins are compounds that produce a wide variety of growth responses in flowering plants. Among these responses are stimulation of shoot growth for many plant species,' root elongation in maize,2 induction of bolting and flowering in some biennial and long-day plants,3-resumption of normal growth in certain genetically dwarfed genotypes of maize,6 growth stimulation in dwarf strains of pe...

Plant hormones modulate plant growth, development, and defense. However, many aspects of the origin and evolution of plant hormone signaling pathways remain obscure. Here, we use a comparative genomic and phylogenetic approach to investigate the origin and evolution of nine major plant hormone (abscisic acid, auxin, brassinosteroid, cytokinin, ethylene, gibberellin, jasmonate, salicylic acid, a...

The Arabidopsis hypocotyl, together with hormone mutants and chemical inhibitors, was used to study the role of auxin in cell elongation and its possible interactions with ethylene and gibberellin. When wild-type Arabidopsis seedlings were grown on media containing a range of auxin concentrations, hypocotyl growth was inhibited. However, when axr1-12 and 35S-iaaL (which have reduced auxin respo...

18 Potato virus Y is the most economically important potato viral pathogen. We aimed at 19 unraveling the roles of small RNAs (sRNAs) in the complex immune signaling network 20 controlling the establishment of tolerant response of potato cv. Désirée to the virus. We 21 constructed a sRNA regulatory network connecting sRNAs and their targets to link sRNA 22 level responses to physiological proce...

Two inhibitory fractions (B(1) and C) from extracts of immature fruit of carob were tested for their ability to inhibit the action of indoleacetic acid (IAA) in three bioassays. There was no reduction of IAA-induced reactions in the Avena curvature test, abscission of debladed coleus petioles, or growth of cucumber hypocotyls. The highest ratio of inhibitor to IAA was 10,000 times greater than ...

The major effects of the gibberellins (GA) on plants have been reviewed recently (13, 14) but no definite linkage with any metabolic pathway has been established. In their study of photosynthesis in gibberellin treated leaves Haber and Tolbert (8) concluded that gibberellic acid neither enhanced the rate of CO2 fixation per unit of leaf tissue nor altered the general pathways of short time meta...