During the vegetative propagation of sugarcane by stem portions, two types of roots are produced. First the roots from the quiescent primordia of the radical band of the nodes, and later the roots of the buds. The life span of the first ones is limited, but the sprouting cane and therefore the development of the plant depends on them. The developing root constitutes a very good system to examine the role of the nucleus and its structural organization in plant cell development. The simple cellular architecture and the clearly definable cell lineages within the root, allow cells of the quiescent primordia to be followed and analyzed throughout all stages of their development. The development of the root primordia from the unsoaked quiescent state of the blastema up to the steady state of the proliferative meristem was analyzed in sugar-cane var. Cristaima, which was cultured on wet filter paper, in an incubator at 30 “C with a 80% humidity, in the dark. The activation of the meristematic population was estimated by the mitotic indexes recorded in squashed roots stained by the Feulgen reaction. The kinetics of the proliferation process was calculated by flow cytometry. For the ultrastructural analysis, the meristematic population was localized in semithin section of roots. During the induction of proliferation hnRNA transcription and RNA splicing activities were investigated by immunolabeling at both fluorescence and electron microscopy. A correlation has been established between nuclear organization and activity, and the signification of some structures typical of quiescent cells, like the nuclear fibrillar bundles, have also been established.

Trabajo presentado en el XIV International Congress on Electron Microscopy Photomicrograph Exhibit, celebrado en Cancún (México), del 31 de agosto al 4 de septiembre de 1998