Ultrastructural localization of cellulase in abscission cells of tobacco nicotiana tabacum cultivar little turkish flower pedicels

Lieberman, S.J.; Valdovinos, J.G.; Jensen, T.E.

Botanical Gazette 143(1): 32-40


Accession: 006858889

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Cortical cells within the abscission zone of N. tabacum flower pedicles were examined to identify cellulases at the fine structural level. A cytochemical method reported by Bal et al. for the ultrastructural localization of cellulase was modified and applied to study cell wall breakdown during ethylene-induced abscission and abscission where pollination was prevented. The deposition of Cu, a precipitate of the Benedict's solution-cellulose sugars reaction, was utilized as a marker to detect cellulase activity in the abscission zone cells. The Cu precipitate was present principally in the middle lamella region of the cell wall and, in small amounts, in the primary and secondary regions of the cell wall. Time-course studies for ethylene-treated tissue and tissue where pollination was prevented indicated that cellulase activity was at its highest level during advanced stages of abscission. The break strengths of the abscission zone decreased prior to the increase in cellulase activity for ethylene-treated tissue and tissue where pollination was prevented. Tubular fibril and regular fibril arrangement patterns were present in cell walls of abscission zone cells. Electron-dense bodies were associated with cell wall fibrils. Lipid bodies in the cytoplasm near wall regions increased in frequency during the latter stages of abscission.