Changes in Microtubules in Onion Leaf Sheath Cells during Bulb Development

Abstract

Cortical microtubules are oriented transversely to the cell axis in leaf sheath cells of onion plants (Allium cepa L. cv. Osaka-Okute) that have not started bulb formation. As the bulb develops and the leaf sheath cells swell, the microtubules become disoriented and scattered and finally disappear. The microtubule inhibitors colchicine and cremart [O-ethyl O-(3-methyl-6-nitrophenyl)N-sec-butylphosphorothioamidate] cause swelling of leaf sheath cells and make the basal part of the plant bulbous. The cortical microtubules may have an important role in regulating bulb development in onion plants.