Petra Stirnberg

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Plant shoots elaborate their adult form by selective control over the growth of both their primary shoot apical meristem and their axillary shoot meristems. We describe recessive mutations at two loci in Arabidopsis, MAX1 and MAX2, that affect the selective repression of axillary shoots. All the first order (but not higher order) axillary shoots initiated(More)
The plant shoot body plan is highly variable, depending on the degree of branching. Characterization of the max1-max4 mutants of Arabidopsis demonstrates that branching is regulated by at least one carotenoid-derived hormone. Here we show that all four MAX genes act in a single pathway, with MAX1, MAX3, and MAX4 acting in hormone synthesis, and MAX2 acting(More)
Transcription of the AUX/IAA family of genes is rapidly induced by the plant hormone auxin, but evidence that AUX/IAA genes mediate further responses to auxin has been elusive. Changes in diverse auxin responses result from mutations in the Arabidopsis AXR3 gene. AXR3 was shown to be a member of the AUX/IAA family, providing direct evidence that AUX/IAA(More)
In Arabidopsis (Arabidopsis thaliana), the carotenoid cleavage dioxygenases MORE AXILLARY GROWTH3 (MAX3) and MAX4 act together with MAX1 to produce a strigolactone signaling molecule required for the inhibition of axillary bud outgrowth. We show that both MAX3 and MAX4 transcripts are positively auxin regulated in a manner similar to the orthologous genes(More)
Apically derived auxin has long been known to inhibit lateral bud growth, but since it appears not to enter the bud, it has been proposed that its inhibitory effect is mediated by a second messenger. Candidates include the plant hormones ethylene, cytokinin and abscisic acid. We have developed a new assay to study this phenomenon using the model plant(More)
The AXR1 gene of Arabidopsis is required for many auxin responses. The highly branched shoot phenotype of mature axr1 mutant plants has been taken as genetic evidence for a role of auxin in the control of shoot branching. We compared the development of lateral shoots in wild-type Columbia and axr1-12 plants. In the wild type, the pattern of lateral shoot(More)
The Arabidopsis gene ORE9/MAX2 encodes an F-box leucine-rich repeat protein. F-box proteins function as the substrate-recruiting subunit of SCF-type ubiquitin E3 ligases in protein ubiquitination. One of several phenotypes of max2 mutants, the highly branched shoot, is identical to mutants at three other MAX loci. Reciprocal grafting, double mutant analysis(More)
Axillary meristems form in the axils of leaves. After an initial phase of meristematic activity during which a small axillary bud is produced, they often enter a state of suspended growth from which they may be released to form a shoot branch. This post-embryonic growth plasticity is typical of plants and allows them to adapt to changing environmental(More)
Branching plays an important role in the elaboration of plant adult body plans. The shoots of higher plants are characterised by axillary branching, where branches develop from axillary shoot meristems located between a leaf and the shoot axis. Variation of the pattern of axillary shoot meristem initiation and activity contributes to the diversity of plant(More)
The plant hormone auxin exerts many of its effects on growth and development by controlling transcription of downstream genes. The Arabidopsis gene AXR3/IAA17 encodes a member of the Aux/IAA family of auxin responsive transcriptional repressors. Semi-dominant mutations in AXR3 result in an increased amplitude of auxin responses due to hyperstabilisation of(More)