Seed dormancy is an adaptive mechanism that allows seed germination under suitable environmental conditions. Germination of stored dormant seeds proceeds after dormancy breaking induced by stratification. To improve understanding of dormancy breaking in beechnuts, we: investigated effects of moisture content and temperature during storage; analysed contents of abscisic acid, abscisic acid metabolites and indole-3-acetic acid in embryonic axes during storage and stratification; and histochemically localized storage proteins in embryogenic axes and cotyledons of beechnut embryos. The results show that storage conditions can affect the nuts’ abscisic acid contents, but not the stratification process. In addition, dormancy breaking is linked to a reduction in abscisic acid contents and depth of dormancy is not influenced by either of these storage factors. Detected changes that correlated most strongly with dormancy breaking were a big increase in abscisic acid-glucosyl ester levels and accompanying reduction in the abscisic acid-glucosyl ester to abscisic acid ratio. We detected extremely low concentrations of other abscisic acid metabolites-neophaseic, phaseic and dihydrophaseic acids—in non-dormant stored beechnuts, but somewhat higher concentrations during dormancy. No relationships between changes in indole-3-acetic acid levels with either storage conditions or dormancy breaking were detected. Changes in distributions of storage proteins were related to the seeds’ moisture content during storage and stratification rather than seed dormancy. We conclude that increases in endogenous abscisic acid-glucosyl ester levels and abscisic acid-glucosyl ester to abscisic acid ratios are good markers of depth of dormancy and/or effectiveness of stratification in beechnuts.

中文翻译：

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冬青种子的休眠中断与脱落酸-葡萄糖基酯的形成有关

种子休眠是一种适应性机制，可使种子在合适的环境条件下发芽。分层导致的休眠中断后，休眠的种子继续发芽。为了更好地了解山毛榉木中休眠的破坏，我们：研究了水分含量和温度在储存过程中的影响；分析了贮藏和分层过程中胚轴中脱落酸，脱落酸代谢产物和吲哚-3-乙酸的含量；和组织化学定位的存储蛋白在山毛榉胚胎的胚发生轴和子叶中。结果表明，贮藏条件会影响坚果的脱落酸含量，但不会影响分层过程。此外，休眠中断与脱落酸含量的减少有关，并且休眠深度不受这两个存储因素的影响。检测到的与休眠中断最密切相关的变化是脱落酸-葡糖基酯水平的大幅增加以及伴随的脱落酸-葡糖基酯与脱落酸比例的降低。我们在非休眠的榉木中检测到极低浓度的其他脱落酸代谢物（新相，相和二氢相酸），而在休眠过程中则检测到较高的浓度。没有发现吲哚-3-乙酸水平的变化与储存条件或休眠中断之间的关系。贮藏蛋白分布的变化与贮藏和分层过程中种子的水分含量有关，而不是与种子休眠有关。