Abstract：
Ex situ preservation of genetic resources is an essential strategy for the conservation of plant biodiversity. In this regard, seed storage is the most convenient and efficient way of preserving germplasm for future plant breeding efforts. A better understanding of the molecular changes that occur during seed desiccation and aging is necessary to improve conservation protocols, as well as real-time methods for monitoring seed quality. In the present study, we assessed changes in the level of genomic 5-methylcytosine (5mC) in seeds of Populus nigra L. by 2D-TLC. Epigenetic changes were characterized in response to several seed storage regimes. Our results demonstrate that P. nigra seeds represent an intermediate type of post-harvest behavior, falling between recalcitrant and orthodox seeds. This was also true for the epigenetic response of P. nigra seeds to external factors. A crucial question is whether aging in seeds is initiated by a decline in the level of 5mC, or if epigenetic changes induce a process that leads to deterioration. In our study, we demonstrate for the first time that 5mC levels decrease during storage and that the decline can be detected before any changes in seed germination are evident. Once P. nigra seeds reached an 8-10% reduction in the level of 5mC, a substantial decrease in germination occurred. The decline in the level of 5mC appears to be a critical parameter underlying the rapid deterioration of intermediate seeds. Thus, the measurement of 5mC can be a fast, real-time method for assessing asymptomatic aging in stored seeds.
摘要：
遗传资源的异地保存是保护植物生物多样性的重要策略。在这方面,种子储存是今后植物育种工作中最方便、最有效的种质保存方式。更好地了解种子干燥和老化过程中发生的分子变化对于改善保护方案是必要的。以及实时监测种子质量的方法。在本研究中,我们通过2D-TLC评估了黑杨种子中基因组5-甲基胞嘧啶（5mC）水平的变化。表观遗传变化的特征是响应几种种子储存方式。我们的结果表明，黑草种子代表了一种中间类型的收获后行为，落在顽固和正统的种子之间。黑草种子对外部因素的表观遗传反应也是如此。一个关键问题是种子的老化是否由5mC水平的下降引发，或者表观遗传变化诱导导致恶化的过程。在我们的研究中,我们首次证明了5mC水平在储存过程中下降，并且在种子发芽明显变化之前可以检测到下降。一旦黑假单胞菌种子在5mC的水平上达到8-10%的降低，发芽大幅减少。5mC水平的下降似乎是中间种子快速变质的关键参数。因此，5mC的测量可以是快速的，用于评估储存种子中无症状老化的实时方法。
