Cytokinin is required for escape but not release from auxin mediated apical dominance
| Autor: | Dörte Müller, Ottoline Leyser, Tatsuo Kakimoto, Charles W. Melnyk, Tanya Waldie, Jennifer P.C. To, Kaori Miyawaki, Joseph J. Kieber |
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| Rok vydání: | 2015 |
| Předmět: |
0106 biological sciences
Cytokinins Arabidopsis thaliana Apical dominance Mutant Arabidopsis Plant Science 01 natural sciences apical dominance cytokinin 03 medical and health sciences chemistry.chemical_compound Gene Expression Regulation Plant Auxin Axillary bud Botany Genetics shoot branching Isopentenyltransferase 030304 developmental biology chemistry.chemical_classification 0303 health sciences Alkyl and Aryl Transferases Nitrates Indoleacetic Acids biology Arabidopsis Proteins fungi food and beverages Original Articles Cell Biology biology.organism_classification Cell biology chemistry Multigene Family Mutation Shoot Cytokinin type-A Arabidopsis response regulators auxin Plant Shoots Transcription Factors 010606 plant biology & botany |
| Zdroj: | The Plant Journal |
| ISSN: | 0960-7412 |
| DOI: | 10.1111/tpj.12862 |
| Popis: | Auxin produced by an active primary shoot apex is transported down the main stem and inhibits the growth of the axillary buds below it, contributing to apical dominance. Here we use Arabidopsis thaliana cytokinin (CK) biosynthetic and signalling mutants to probe the role of CK in this process. It is well established that bud outgrowth is promoted by CK, and that CK synthesis is inhibited by auxin, leading to the hypothesis that release from apical dominance relies on an increased supply of CK to buds. Our data confirm that decapitation induces the expression of at least one ISOPENTENYLTRANSFERASE (IPT) CK biosynthetic gene in the stem. We further show that transcript abundance of a clade of the CK-responsive type-A Arabidopsis response regulator (ARR) genes increases in buds following CK supply, and that, contrary to their typical action as inhibitors of CK signalling, these genes are required for CK-mediated bud activation. However, analysis of the relevant arr and ipt multiple mutants demonstrates that defects in bud CK response do not affect auxin-mediated bud inhibition, and increased IPT transcript levels are not needed for bud release following decapitation. Instead, our data suggest that CK acts to overcome auxin-mediated bud inhibition, allowing buds to escape apical dominance under favourable conditions, such as high nitrate availability. Significance Statement It has been proposed that the release of buds from auxin-mediated apical dominance following decapitation requires increased cytokinin biosynthesis and consequent increases in cytokinin supply to buds. Here we show that in Arabidopsis, increases in cytokinin appear to be unnecessary for the release of buds from apical dominance, but rather allow buds to escape the inhibitory effect of apical auxin, thereby promoting bud activation in favourable growth conditions. |
| Databáze: | OpenAIRE |
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