ASGSB 1999 Annual Meeting Abstracts

THE INTERACTIONS OF TOUCH AND GRAVITY IN PLANT ROOTS AS THEY ENCOUNTER AN OBSTACLE. G.D. Massa and S. Gilroy. Dept of Biology, Penn State University.

Plant roots in nature may encounter many barriers, such as rocks, in the normal course of downward growth. A response to obstacles requires reorientation of the growing root until unobstructed vertical growth can resume. We have therefore studied the cellular localization of sensing, and the response kinetics, of roots growing under these conditions. The rate of elongation and the angle of the root tip were measured, before, during, and after the root encountered the barrier. The response of an Arabidopsis thaliana root to a rigid obstacle appears to be mediated by a combination of touch and gravity sensing via the root cap, with a growth response occurring in the elongation zone. Laser ablation studies demonstrate that peripheral cap cells are necessary for a normal touch response in roots. Gravisensing is also required for normal bend formation, however the touch component of the response can function without gravisensitivity. Data with mutant plants and other species is consistent with a requirement for both touch and gravity sensitivity in this growth response.

This research was supported by NSF.

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