Molecular characterization of cytokinin-responsive histidine kinases in maize. Differential ligand preferences and response to cis-zeatin

Keiko Yonekura-Sakakibara, Mikiko Kojima, Tomoyuki Yamaya, Hitoshi Sakakibara

    Research output: Contribution to journalArticle

    148 Citations (Scopus)

    Abstract

    Genes for cytokinin-responsive His-protein kinases (ZmHK1, ZmHK2, and ZmHK3a) were isolated from maize (Zea mays). Heterologous expression of each of the ZmHKs in Escherichia coli having the ΔrcsC and cps::lacZ genetic background conferred cytokinin-inducibility of lacZ expression on the bacteria. In the recombinant E. coli system, ZmHK1 and ZmHK3a were more sensitive to free-base cytokinins than to the corresponding nucleosides; isopentenyladenine was most effective for ZmHK1, while ZmHK2 tended to be most sensitive to trans-zeatin and the riboside. In contrast to a known cytokinin receptor of Arabidopsis (AHK4/CRE1/WOL), all ZmHKs responded to cis-zeatin (cZ), which generally is believed to be inactive or only weakly active. In cultured maize cells, expression of ZmRR1, a cytokinin-inducible response regulator, was induced by cZ as well as by trans-zeatin. These results strongly suggest that maize cytokinin receptors differ in ligand preference, and that cZ is an active cytokinin at least in maize.

    Original languageEnglish
    Pages (from-to)1654-1661
    Number of pages8
    JournalPlant physiology
    Volume134
    Issue number4
    DOIs
    Publication statusPublished - 2004 Apr

    ASJC Scopus subject areas

    • Physiology
    • Genetics
    • Plant Science

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