Immunogold electron-microscopy localization of abscisic acid in flesh cells of grape berry (Vitis vinifera L. x Vitis labrusca L. cv Kyoho)

The immunogold electron-microscopy technique was used to determine the subc ellular localization of abscisic acid (ABA) in flesh cells of grape berry ( Vitis vinifera L. x Vitis labrusca L. cv. Kyoho). The results showed that, mainly, there existed two kinds of cells in the flesh of the grape berry: c ells containing a large amount of phenolic compounds (phenol-rich cell) and those containing no phenolic compounds (non-phenol cells). In the phenol r ich cells, both the nucleus and cytoplasm were heavily labeled by gold part icles; mon gold particles were found in the nucleus when compared with the cytoplasm and other parts, and the cell wall was labeled by few particles. In the vacuole of the phenol-rich cells, the phenol-distributed areas were somehow labeled by gold particles, and the labeling density was somewhat di fferent with the state changes of phenolic compounds. The labeling picture of gold particles to the non-phenol cells was similar to that of the phenol -rich cells, but no gold particle was observed in the vacuole of the non-ph enol cells. The control experiments demonstrated that the immunogold locali zation of ABA was specific and reliable. The compartmentation of PLEA in th e flesh cells and its possible physiological significance were discussed. ( C) 1999 Published by Elsevier Science B.V. All rights reserved.