Microtubule organization of in situ and isolated generative cells in Zephyranthes grandiflora Lindl

Microtubule organization in the generative cells of Zephyranthes grandiflora was investigated by immunofluorescence microscopy with a monoclonal anti-α-tubulin. The experimental materials used were generative cells located within pollen grains and tubes (i.e., in situ) as well as those artificially isolated after osmotic shock or grinding treatments of the pollen grains. Diverse microtubule organization patterns were revealed. In situ, the generative cells appeared spindle-shaped and contained mainly longitudinally oriented microtubule bundles, although other types were found as well. After isolation, as the alteration in microtubule patterns took place, the spindle-shaped generative cells became ellipsoidal and then spherical. In the ellipsoidal cells a transitional form consisting of a mixture of microtubule bundles and meshes could be found. In spherical cells the mesh structure appeared to be the predominant pattern. These results indicate that the microtubule cytoskeleton of the generative cells can change easily from one structural form to another in accordance with environmental conditions and may play an important role in determining the cell shape.