ISHS Acta Horticulturae 591: III International Symposium on Pistachios and Almonds
THE MICROSCOPY OF TISSUE DECOLOURATION AND BROWNING PROBLEM IN PISTACHIO CALLUS CULTURES |
| Authors: | A. Vatanpour-Azghandi, T.A. Villiers, A.M. Ghorbani, A. Tajabadi |
| Keywords: | callus culture, browning, polyphenolic materials, vacuole, vesicles, cytoplasm. |
| Abstract:
Browning of the pistachio explants, older callus growth and the culture medium around the explants was found to be a problem in our study, during both the callus initiation stage and during callus proliferation and growth. Since there is no direct published information available, it was therefore considered interesting to obtain some basic information on the origin, intercellular distribution, and destination of polyphenolics during callus formation of pistachio (P. vera cv 'Ghazvini'). Specimens from pistachio leaf explants before and after culture on callus induction medium and at about 10 day intervals were fixed in 2.5% glutaraldehyde, embedded in Spurr resin, sectioned using an L.K.B. ultramicrotome, and stained following standard procedures. The observations showed that in both the cells of the original leaf explants and in callus cells, dense granular deposits appeared within the cell cytoplasm. It was found that the vacuoles of many adjacent cells had become heavily loaded with electron-dense polyphenolic deposits. The movement of polyphenolic deposits from cytoplasm into the main vacuole was evident, where they became closely associated with the inner face of the vacuole membrane and later occurred as large masses within each vacuole. The polyphenolic pigments were never seen free in the cytoplasm, but appeared to be formed, deposited, or at least became concentrated into dense masses within vacuoles, or in vesicles which became assimilated into the cell vacuole. The phenolic material was never seen to be discharging from either the vacuole into the cytoplasm, or passing from any cell to the exterior. The tissues in which the cell developed these deposits had fewer cell divisions, divided without separation of cells, and with little or no cell enlargement. | |
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