Journal Article

The Pea TCP Transcription Factor PsBRC1 Acts Downstream of Strigolactones to Control Shoot Branching

de Saint Germain, Alexandre, Dalmais, Marion, Luo, Da, Rameau, Catherine, Braun, Nils, Le Signor, Christine, Li, Xin, Boutet-Mercey, Stéphanie, Bouteiller, Nathalie, Antoniadi, Ioanna, Turnbull, Colin, Bendahmane, Abdelhafid, Pillot, Jean-Paul, Maia-Grondard, Alessandra

2012

Overview

The function of PsBRCl, the pea (Pisum sativum) homolog of the maize (Zea mays) TEOSINTE BRANCHED1 and the Arabidopsis (Arabidopsis thaliana) BRANCHED1 (AtBRC1) genes, was investigated. The pea Psbrc1 mutant displays an increased shoot-branching phenotype, is able to synthesize strigolactone (SL), and does not respond to SL application. The level of pleiotropy of the SL-deficient ramosus1 (rms1) mutant is higher than in the Psbrcl mutant, rms1 exhibiting a relatively dwarf phenotype and more extensive branching at upper nodes. The PsBRCl gene is mostly expressed in the axillary bud and is transcriptionally up-regulated by direct application of the synthetic SL GR24 and down-regulated by the cytokinin (CK) 6-benzylaminopurine. The results suggest that PsBRCl may have a role in integrating SL and CK signals and that SLs act directly within the bud to regulate its outgrowth. However, the Psbrcl mutant responds to 6-benzylaminopurine application and decapitation by increasing axillary bud length, implicating a PsBRCl -independent component of the CK response in sustained bud growth. In contrast to other SL-related mutants, the Psbrcl mutation does not cause a decrease in the CK zeatin riboside in the xylem sap or a strong increase in RMS1 transcript levels, suggesting that the RMS2-dependent feedback is not activated in this mutant. Surprisingly, the double rmsl Psbrcl mutant displays a strong increase in numbers of branches at cotyledonary nodes, whereas branching at upper nodes is not significantly higher than the branching in rmsl. This phenotype indicates a localized regulation of branching at these nodes specific to pea.

• Publisher: American Society of Plant Biologists
• Subject: analogs & derivatives / Arabidopsis Proteins / Arabidopsis Proteins - metabolism / Arabidopsis thaliana / Auxins / Benzyl Compounds / benzyladenine / Biological and medical sciences / branches / Branching / buds / corn / Cytokinins / Cytokinins - genetics / Cytokinins - metabolism / DEVELOPMENT AND HORMONE ACTION / drug effects / Fundamental and applied biological sciences. Psychology / Gene expression regulation / Gene Expression Regulation, Plant / Genes / Genetic mutation / genetics / Genotypes / growth & development / Isopentenyladenosine / Isopentenyladenosine - analogs & derivatives / Isopentenyladenosine - metabolism / Kinetin / Kinetin - pharmacology / Lactones / Lactones - metabolism / metabolism / Molecular Sequence Data / mutants / Mutation / Peas / pharmacology / phenotype / Phenotypes / Pisum sativum / Pisum sativum - drug effects / Pisum sativum - genetics / Pisum sativum - growth & development / Pisum sativum - metabolism / Plant Growth Regulators / Plant Growth Regulators - pharmacology / Plant physiology and development / Plant Proteins / Plant Proteins - genetics / Plant Proteins - metabolism / Plant Shoots / Plant Shoots - genetics / Plant Shoots - growth & development / Plant Shoots - metabolism / Plants / Purines / Rice / sap / shoots / Signal Transduction / Signal Transduction - genetics / transcription factors / Transcription Factors - genetics / Transcription Factors - metabolism / Up-Regulation / xylem / Xylem - genetics / Xylem - metabolism / Zea mays / zeatin