期刊
PLANT JOURNAL
卷 82, 期 5, 页码 874-886出版社
WILEY
DOI: 10.1111/tpj.12862
关键词
cytokinin; auxin; shoot branching; apical dominance; Arabidopsis thaliana; Isopentenyltransferase; type-A Arabidopsis response regulators
资金
- UK Biotechnology and Biological Sciences Research Council via the European Research Area Plant Genomics programme [R1039101]
- European Research Council [294514 - EnCoDe]
- Gatsby Foundation [GAT3272C]
- US National Science Foundation [IOS1022053]
- Japan Society for the Promotion of Science [15107001]
- Ministry of Education, Sports, Science, and Technology [17027017]
- Precursory Research for Embryonic Science and Technology, Japan Science and Technology
- BBSRC [BB/E024750/1] Funding Source: UKRI
- Grants-in-Aid for Scientific Research [17027017, 15107001, 25113006] Funding Source: KAKEN
- Division Of Integrative Organismal Systems
- Direct For Biological Sciences [1022053] Funding Source: National Science Foundation
- Biotechnology and Biological Sciences Research Council [BB/E024750/1] Funding Source: researchfish
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.
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