title: AXR1 acts after lateral bud formation to inhibit lateral bud growth in Arabidopsis.
abstract: 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 development depends on the developmental stage of the plant. During prolonged vegetative growth, axillary shoots arise and develop in a basal-apical sequence. After floral transition, axillary shoots arise rapidly along the primary shoot axis and grow out to form lateral inflorescences in an apical-basal sequence. For both patterns, the axr1 mutation does not affect the timing of axillary meristem formation; however, subsequent lateral shoot development proceeds more rapidly in axr1 plants. The outgrowth of lateral inflorescences from excised cauline nodes of wild-type plants is inhibited by apical auxin. axr1-12 nodes are resistant to this inhibition. These results provide evidence for common control of axillary growth in both patterns, and suggest a role for auxin during the late stages of axillary shoot development following the formation of the axillary bud and several axillary leaf primordia.
authors.affiliation: Department of Biology, University of York, P.O. Box 373, York YO10 5YW, United Kingdom.
authors.forename: P
authors.initials: P
authors.lastname: Stirnberg
authors.forename: S P
authors.initials: SP
authors.lastname: Chatfield
authors.forename: H M
authors.initials: HM
authors.lastname: Leyser
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins; D006133:Growth Substances; D018519:Meristem / Q000502:physiology; D017440:Photoperiod; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018520:Plant Shoots / Q000502:physiology
chemical_list: C081977:AXR1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D006133:Growth Substances; D010940:Plant Proteins