Document: OME-3-33-12

Root navigation by self-inhibition.

FALIK, O.*, M.GERSANI and A.NOVOPLANSKY

Ben-Gurion University of the Negev, Israel ¹

Abstract:
Physical obstacles influence the development and architecture of roots. When bean plants were grown with their main roots near vertical bamboo sticks or thin nylon threads they developed asymmetrically, allocating less in secondary roots facing the physical obstacles. We hypothesized that roots are capable of perceiving and avoiding inanimate objects by secreting self-inhibiting substance(s) that accumulate near the obstacles. The development of bean roots was followed near inanimate obstacles with or without the exclusion of root exudates from the medium. Plants were grown in vermiculite with their main roots facing cellulose dialysis tubes filled up with activated carbon on one side and non-activated carbon on the other. Although the number of secondary roots was the same towards both hemicylinders, their average length was significantly greater in the direction of the activated carbon. A similar response was observed in preliminary experiments when the activated carbon was replaced by KMnO₄ known as an absorbent of ethylene. The results suggest that obstacle-avoidance behavior of roots might be based on self-inhibition of roots by their own exudates that are accumulating near inanimate objects, and that ethylene might be one of these exudates. This mechanism allows roots avoiding resource allocation towards less promising directions.

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This abstract is being presented at: 3:30 PM in session:
ROOT PROCESSES