1999 Volume 64 Issue 2 Pages 215-221
The behavior of the vegetative nucleus during pollen grain development and germination in Tropaeolum majus was examined using epifluorescence microscopy stained with 4', 6-di-amidino-2-phenylindole (DAPI). The vegetative nucleus exhibited gradual elongation and overall length association with the simultaneously elongated generative cell during pollen development. The elongated vegetative nucleus and generative cell in the mature pollen grains appeared in a paired structure that was stable against physically squashed pollen rupture. Electron microscopy showed that the ultrastructural relationship between the vegetative nucleus and the generative cell was discontinuous with rough endoplasmic reticulum (RER) often located in the interface and Golgi bodies appeared remarkably around the generative cell. However, the vegetative nucleus became spherical after pollen hydration and the association between the vegetative nucleus and the generative cell disintegrated markedly during pollen germination. These results suggest that the elongation of the vegetative nucleus and the physical association between the vegetative nucleus and the generative cell in the pollen grains of T majus may play an important role in pollen, especially the generative cell development.