Gravitropic response plays an important role in the nutational movements of the shoots of Pharbitis nil and Arabidopsis thaliana

Yasuko Hatakeda, Motoshi Kamada, Nobuharu Goto, Hidehiro Fukaki, Masao Tasaka, Hiroshi Suge, Hideyuki Takahashi

    Research output: Contribution to journalArticlepeer-review

    40 Citations (Scopus)

    Abstract

    The shoots of a Japanese strain of morning glory (Pharbitis nil) called 'Shidare-asagao' display agravitropic and weeping growth. It has been shown that this shoot agravitropism may be due to the defective differentiation of endodermal cells that contain statoliths. Roots of the weeping morning glory show normal responsiveness to gravity and the shoots are positively phototropic. Shoots of the morning glory cultivar Violet used as a wild type exhibited distinct circumnutation with circular movements that increase as the plants grow. In weeping morning glory, however, nutation was limited to slight back and forth or side to side movements. To determine whether endodermal cells participate in circumnutation through a function that is independent of their role in gravitropism, the nutational movements of various gravitropic mutants of Arabidopsis thaliana were compared. The inflorescences of wild-type Arabidopsis showed relatively large circular movements. Inflorescences of the pgm-1 mutant, which is defective in starch synthesis, showed reduced nutation. Even more seriously affected were the sgr1-1/scr-3 and sgr7-1/shr-2 mutants, which are defective in endodermal cell differentiation, and the auxin-resistant axr2-1 mutant showed no significant nutational movements at all. 1-N-naphthylphthalamic acid (NPA) could inhibit Violet circumnutation, supporting the notion that auxin participates in circumnutation. Thus, the gravitropic response is an essential component in plant shoot circumnutation. Endodermal cells are involved in such circumnutation possibly because of their role in inducing the gravitropic response.

    Original languageEnglish
    Pages (from-to)464-473
    Number of pages10
    JournalPhysiologia Plantarum
    Volume118
    Issue number3
    DOIs
    Publication statusPublished - 2003 Jul 1

    ASJC Scopus subject areas

    • Physiology
    • Genetics
    • Plant Science
    • Cell Biology

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