Relationship between the levels of abscisic acid in latent buds, in leaves and in internodes of <em>Vitis vinifera</em> L. cv. Merlot during the dormancy phase

The levels of free and bound ABA (cis-ABA and cis-ABA-GE) were quantified weekly during the dormancy phase of three years in leaves, in latent buds and in internodes grapevine (Vitis vinifera L. cv. Merlot) by high pressure liquid chromatography (HPLC). An inverse variation between cis-ABA and cis-ABA-GE levels was observed in buds and in internodes during some phases of their development. This result seems suggest a possible interconversion phenomenon between these two ABA forms as described in others organs by some authors. The development of ABA in leaves, in buds and in internodes, showed three successive maximums of cis-ABA. The first maximum was observed in leaves during onset of dormancy, the second maximum in buds during dormancy and the last in internodes during the leaf fall. Maximums of cis-ABA in leaves and in buds are approximatively the some values (around of 150 µg/100 g Dry Weight) whereas in internodes is lower (60 µg/100 g Dry Weight). An inverse variation between cis-ABA of leaves and cis-ABA of buds was observed suggesting that the increase of cis-ABA in buds was caused by the cis-ABA translocation from leaves but also from roots. The removal of leaves on september 1997 during the dormancy phase, before leaf fall period, induced an increase of cis-ABA content in buds and internodes. These results seem suggest that before leaf fall period, ABA of buds and internodes were translocated to leaves. During this same period, the removal of leaves and buds induced a slightly soften of ABA content increase in internodes, that seems indicate that ABA was greatly translocated from roots. During the period of leaf fall, the leaf removal traitment induced a decrease of cis-ABA levels in buds and in internodes while the same traitment associated to buds removal stabilized the ABA levels in internodes. During this period, ABA seems exported from leaves to buds and internodes and the roots don't appear to operate significantly in the development of ABA in these two organs.