Bound and Free Abscisic Acid Levels in Dormant and After-ripened Embryos of Pyrus malus L. cv. Golden delicious

Abscisic acid relationships in the chill-related dormancy mechanism in apple seeds

“…Left unanswered, however, are the findings of [2] that conversion of ABA to its inactive glucose complex may be an important mechanism regulating ABA content in the stratification process. Our studies, which did not encompass the ABA/ABA-glucose interconversion process, suggest that leaching of ABA accounts for most of its decline in the seed during stratification, but only additional studies can clarify the relative importance of the various mechanisms which regulate ABA content.…”

“…Where germination and ABA changes were either not correlated or inconsistent, the importance of ABA in the dormancy mechanism was questioned [l, 8, 161. However, Barthe and Bulard [2], finding conversion of free ABA to a bound form during cold stratification, suggested that release from dormancy was related to this metabolic conversion.…”

“…For instance, Rudnicki [ 171 found only traces of ABA in dormant apple embryos, whereas Barthe and Bulard [2] detected much higher quantities. Balboa-Zavala and Dennis [1] found relatively small changes in ABA in the seed coat and cotyledons of apple during stratification, but Lee and Looney [8] found that the ABA in the seed coat and nucellar membrane increased markedly during early stratification and then decreased, while ABA declined in the embryo.…”

Distribution of free and bound forms of cis‐trans and trans‐trans abscisic acid in broad‐bean plants in relation to apical dominance

“…Only in the cotyledonary node did the levels of ABA tend to be greater than in the above tissues ( Fig, 2A), These results were anticipated by our previous experiments on endogenous (Everat-Bourbouloux and Charnay 1982) (Dumbroff et al, 1979) and bean (Weiler 1980), while ABA reached between 2 and 3 |ig (g fresh weight) ' (8 to 11 ^^/) in the apical part of dormant birch branches (Dathe et al, 1984), In this latter species, as well as in bean (Horemans et al, 1986) and in Vicia (our experiments), a decrease of ABA concentration occurred along the stem with increasing thickness. These high levels of abscisic acid in the upper parts of the stem could be explained by the continuous arrival of the hormone from the phloem (Hoad 1973, Zeevaart 1977, Everat-Bourbouloux 1982 or by xylem flow (Lenton et al, 1968, Alvim et al, 1976 as it occurs in young leaves (Cornish and Zeevaart 1984), Free ABA in the buds When collected for experimentation, the broad-bean plants were in the exponential phase of development, and the apical bud was actively growing. The weight of the buds differed along the stem: Bud ax, was the lightest and ax; the heaviest, whereas ax, and the cotyledonary buds were intermediate (Tab, 1), When expressed on a whole organ basis (data not shown), the incompletely inhibited buds ax, contained much more free ABA than the completely inhibited and very small bud ax, or than the actively growing apical bud.…”

Le réticulum endoplasmique dans le méristème radiculaire de l'embryon de Pommier (Pirus malusL.): son évolution pendant la levée de dormance au froid

“…1968(COME et coll. , 1969DURAND, 1974;LEWAK et coll., 1975;TISSAOUI, 1975;BARTHE et BULARD, 1978 ;ISAIA et BULARD, 1978 ;DAWIDOWICZ.GRZEGORZEWSKA et LEWAK, 1978;PERINO, 1978;WEISMAN, 1979 ;THÉVENOT, 1980), mais à notre connaissance, aucune étude ultrastructurale de ce matériel n'a été faite. Il nous a donc paru intéressant d'entreprendre une telle étude et de comparer nos résultats avec ceux obtenus par DEREUDDRE (1971,1972) Les fruits de Pommier sauvage, récoltés en octobre en forêt de Fontainebleau, ont été maintenus au-dehors jusqu 'en février.…”