Root navigation by self inhibition

Authors

  • OMER FALIK,

    1. Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel and
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    • *Pennsylvania State University, Department of Horticulture, 103 Tyson Building. University Park, PA, 18602–4200, USA

  • PERLA REIDES,

    1. Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel and
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  • MORDECHAI GERSANI,

    1. Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel and
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  • ARIEL NOVOPLANSKY

    Corresponding author
    1. Mitrani Department of Desert Ecology, Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 84990, Israel
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Ariel Novoplansky. Fax: + 972 8 6596821; e-mail: anovopla@bgumail.bgu.ac.il

ABSTRACT

Circumventing physical obstacles is critical for a plant's survival and performance. Although the ability of roots to circumvent obstacles has been known for over 100 years, the phenomena and its mechanisms have received relatively little attention. In this study it is demonstrated that roots of Pisum sativum are able to detect and avoid growth towards inanimate obstacles and the hypothesis that this behaviour is based on the sensitivity of roots to their own allelopathic exudates that accumulate in the vicinity of physical obstacles is tested. The development of lateral roots of Pisum sativum towards an obstacle (a piece of nylon string, similar in dimensions to a plant root) was followed. Lateral roots were similar in number, but significantly shorter in the direction of the nylon string. In addition, up to half of the lateral roots that developed towards the nylon string withered, whereas no withering was observed in the absence of the nylon string. These avoidance growth patterns were suppressed in the presence of potassium permanganate or activated carbon, indicating a role of allelopathic exudates in promoting obstacle avoidance. The demonstrated obstacle avoidance by self inhibition could increase plant performance by limiting resource allocation to less promising parts of the root system.

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