Auxin-induced longitudinal-to-transverse reorientation of cortical microtubules in nonelongating epidermal cells of azuki bean epicotyls

In epidermal cells of azuki bran (Vigna angularis) epicotyl segments, that were sequentially treated with an auxin-free solution and an auxin solution , cortical microtubules changed their orientation from longitudinal to tran sverse. Auxin caused the reorientation of microtubules from longitudinal to transverse in segments that were kept under anaerobic conditions and, ther efore, showed no elongation, indicating that auxin can regulate the orienta tion of microtubules by a mechanism that does not involve auxin-induced cha nge in the rate of cell elongation.