RRC ID 3797
Author Kitazawa D, Miyazawa Y, Fujii N, Hoshino A, Iida S, Nitasaka E, Takahashi H.
Title The gravity-regulated growth of axillary buds is mediated by a mechanism different from decapitation-induced release.
Journal Plant Cell Physiol
Abstract When the upper part of the main shoot of the Japanese morning glory (Pharbitis nil or Ipomoea nil) is bent down, the axillary bud situated on the uppermost node of the bending region is released from apical dominance and elongates. Here, we demonstrate that this release of axillary buds from apical dominance is gravity regulated. We utilized two agravitropic mutants of morning glory defective in gravisensing cell differentiation, weeping (we) and weeping2 (we2). Bending the main shoots of either we or we2 plants resulted in minimal elongation of their axillary buds. This aberration was genetically linked to the agravitropism phenotype of the mutants, which implied that shoot bending-induced release from apical dominance required gravisensing cells. Previous studies have shown that basipetal translocation of auxin from the apical bud inhibits axillary bud growth, whereas cytokinin promotes axillary bud outgrowth. We therefore compared the roles of auxin and cytokinin in bending- or decapitation-induced axillary bud growth. In the wild-type and we plants, decapitation increased cytokinin levels and reduced auxin response. In contrast, shoot bending did not cause significant changes in either cytokinin level or auxin response, suggesting that the mechanisms underlying gravity- and decapitation-regulated release from apical dominance are distinct and unique.
Volume 49(6)
Pages 891-900
Published 2008-6-1
DOI 10.1093/pcp/pcn063
PII pcn063
PMID 18420594
MeSH Base Sequence Cytokinins / genetics Cytokinins / pharmacology Cytokinins / physiology Gene Expression Regulation, Plant / drug effects Gene Expression Regulation, Plant / physiology Genes, Plant Genes, Reporter Genetic Markers Gravitropism* / drug effects Gravitropism* / genetics Indoleacetic Acids / pharmacology Ipomoea nil / drug effects Ipomoea nil / genetics Ipomoea nil / growth & development* Ipomoea nil / metabolism* Molecular Sequence Data Mutation Plant Growth Regulators / genetics Plant Growth Regulators / pharmacology Plant Growth Regulators / physiology Plant Proteins / genetics Plant Proteins / metabolism Plant Shoots / growth & development
IF 4.062
Times Cited 13
Morning Glory