cis, trans-Abscisic acid (ABA) was identified by combined gas chromatography-mass spectrometry (GC-MS) in a partially purified methanol extract of mature seeds of peach (Prunus persica (L.) Batsch). No germination of intact seeds occurred during seed maturation. Germination of excised embryos increased with maturity, but ABA content of embryonic axes and other seed parts was not related to germination potential. Drying and storage of seeds increased both free and bound ABA in the embryonic axes, but did not significantly affect ABA content of other seed portions. Free and bound ABA decreased on imbibition except for free ABA in the seed coat and bound ABA in the embryonic axis, Levels of free and bound ABA paralleled one another, suggesting that although the former may be converted to the latter, bound ABA is not a major source of free ABA.
The roles of free and bound abscisic acid (ABA) in the breaking of dormancy in seeds of peach (Prunus persica (L.) Batsch) were investigated. Concentrations were consistently 10- to 100-fold higher in the embryonic axes of seeds than in the seed coats or cotyledons. Free and bound ABA declined 75 to 95% during stratification at both 5° and 20°C, yet only the 5° treatment broke dormancy. Extracts of chilled seeds were less inhibitory to germination of non-dormant seeds than were extracts of non-chilled seeds, but ABA content of the extracts was sufficient to account for only a small part of their biological activity.