Plasmodesmata, Tropisms, and Auxin Transport

Abstract

Attempts were made to disrupt the plasmodesmata between oat coleoptile cells (Avena saliva L. cv. Victory) by severe plasmolysis. Coleoptiles, allowed to regain turgor after plasmolysis, were able to execute geotropic and phototropic curvatures and segments would grow in response to applied auxin. In coleoptiles similarly treated, studies with [¹⁴C]IAA have shown that longitudinal, basipetal transport of auxin still takes place and, as in controls, IAA is preferentially redistributed laterally within coleoptiles orientated horizontally. Physical continuity of the symplast of oat coleoptile cells may not always be disrupted by severe plasmolysis. Nevertheless, functional continuity appears to be interrupted. Despite this, all the processes involved in the execution of tropistic curvatures remain intact, including transport of hormones. Plasmodesmatal continuity between oat coleoptile cells appears not to be a necessary requirement for auxin transport.