Strigolactone and cytokinin act antagonistically in regulating rice mesocotyl elongation in darkness

Zhongyuan Hu, Takaki Yamauchi, Jinghua Yang, Yusuke Jikumaru, Tomoko Tsuchida-Mayama, Hiroaki Ichikawa, Itsuro Takamure, Yoshiaki Nagamura, Nobuhiro Tsutsumi, Shinjiro Yamaguchi, Junko Kyozuka, Mikio Nakazono

    Research output: Contribution to journalArticlepeer-review

    37 Citations (Scopus)

    Abstract

    Strigolactones (SLs) are a group of phytohormones that control plant growth and development including shoot branching. Previous studies of the phenotypes of SL-related rice (Oryza sativa) dwarf (d) mutants demonstrated that SLs inhibit mesocotyl elongation by controlling cell division. Here, we found that the expression of cytokinin (CK)-responsive type-A RESPONSE REGULATOR (RR) genes was higher in d10-1 and d14-1 mutants than in the wild type. However, CK levels in mesocotyls of the d mutants were not very different from those in the wild type. On the other hand, application of a synthetic CK (kinetin) enhanced mesocotyl elongation in the d mutants and the wild type. d10-1 and d14-1 mesocotyls were more sensitive to CK than wild-type mesocotyls, suggesting that the up-regulation of the CK-responsive type-A RR genes and the higher elongation of mesocotyls in the d mutants are mainly due to the increased sensitivity of the d mutants to CK. Co-treatment with kinetin and a synthetic SL (GR24) confirmed the antagonistic functions of SL and CK on mesocotyl elongation. OsTCP5, which encodes a transcription factor belonging to the cell division-regulating TCP family, was also regulated by SL and CK and its expression was negatively correlated with mesocotyl length. These findings suggest that OsTCP5 contributes to the SL-and CK-controlled mesocotyl elongation in darkness.

    Original languageEnglish
    Pages (from-to)30-41
    Number of pages12
    JournalPlant and Cell Physiology
    Volume55
    Issue number1
    DOIs
    Publication statusPublished - 2014 Jan 1

    Keywords

    • Cytokinin
    • Mesocotyl
    • Rice
    • Strigolactone

    ASJC Scopus subject areas

    • Physiology
    • Plant Science
    • Cell Biology

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