INFLUENCE OF NITROGEN NUTRITION OF GRAPEVINES ON THEIR POLYAMINE METABOLISM IN FLOWERS AND BERRIES

Abstract

Polyamines (PAs) seem to play an overwhelming role in plant growth and developmental processes. They are found to be essential for cell viability, cell division, prolongation of cell division, and cell elongation and modification (Evans and Malmberg, 1989; Heimer et al. 1979; Mader and Hanke 1997 and Berta et al. 1997). Correlations were found between increase of PA-levels with cell division and a drop in PAs during reduction of metabolic activity (Evans and Malmberg, 1989). Berlin and Forche (1981) reported that low doses of a-DL-difluoromethyl¬ornithine (DFMO) inhibited cell division in tobacco cell cultures, but not their enlargement. Bondi et al. (2000) have reported that the treatment of root cultures of Hyocyamus nutieus with jasmonates increased the putrescine level and also moderately the tropane alkaloid levels. A hypothesis exists that PA’s and ethylene production may regulate each others synthesis, either directly or by metabolic competetion for S-adenosylmethionine (SAM). PA’s inhibit ethylene formation in several plant tissues, i.e. apple fruits, bean and tobacco leaf explants (Apelbaum et al. 1984) Exogenous feeding of putrescine (Put) resulted in reduced ethylene production (Bais et al. 2000a). There exists also some information that PAs are involved in the fertilization process of different plants and their fruit set. Broquedis et al. (1996) could demonstrate that the exogenous application of PAs increased the percentage of fertilization in grape flowers. In the present study complete vine plants (Vitis vinifera L. cv. Riesling) were analysed in their different organs during growing season to achieve an insight in the dynamics of free PAs in that species. The time course of changes in the concentrations of PAs will probably give a better understanding of the flowering and fruit set process in grapevines. The observations were made in a N-fertilizer trial in order to see the additional interactions between nitrogen nutritional status, PAs and fruiting.