Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, Kórnik, 62-035, Poland.
VIB-UGent Center for Medical Biotechnology, VIB, Ghent, B-9052, Belgium.
BMC Plant Biol. 2024 May 8;24(1):377. doi: 10.1186/s12870-024-05085-6.
European beech (Fagus sylvatica L.) trees produce seeds irregularly; therefore, it is necessary to store beech seeds for forestation. Despite the acquisition of desiccation tolerance during development, beech seeds are classified as intermediate because they lose viability during long-term storage faster than typical orthodox seeds. In this study, beech seeds stored for short (3 years) or long (20 years) periods under optimal conditions and displaying 92 and 30% germination capacity, respectively, were compared.
Aged seeds displayed increased membrane damage, manifested as electrolyte leakage and lipid peroxidation levels. Analyses have been based on embryonic axes, which contained higher levels of reactive oxygen species (ROS) and higher levels of protein-bound methionine sulfoxide (MetO) in aged seeds. Using label-free quantitative proteomics, 3,949 proteins were identified, of which 2,442 were reliably quantified pointing to 24 more abundant proteins and 35 less abundant proteins in beech seeds under long-term storage conditions. Functional analyses based on gene ontology annotations revealed that nucleic acid binding activity (molecular function), ribosome organization or biogenesis and transmembrane transport (cellular processes), translational proteins (protein class) and membranous anatomical entities (cellular compartment) were affected in aged seeds. To verify whether MetO, the oxidative posttranslational modification of proteins that can be reversed via the action of methionine sulfoxide reductase (Msr) enzymes, is involved in the aging of beech seeds, we identified and quantified 226 MetO-containing proteins, among which 9 and 19 exhibited significantly up- and downregulated MetO levels, respectively, in beech seeds under long-term storage conditions. Several Msr isoforms were identified and recognized as MsrA1-like, MsrA4, MsrB5 and MsrB5-like in beech seeds. Only MsrA1-like displayed decreased abundance in aged seeds.
We demonstrated that the loss of membrane integrity reflected in the elevated abundance of membrane proteins had a higher impact on seed aging progress than the MetO/Msr system. Proteome analyses enabled us to propose protein Sec61 and glyceraldehyde-3-phosphate dehydrogenase as potential longevity modulators in beech seeds.
欧洲山毛榉（Fagus sylvatica L.）的种子不规则地产生；因此，有必要对山毛榉种子进行贮藏以供造林。尽管在发育过程中获得了干燥耐性，但山毛榉种子被归类为中间型，因为它们在长期储存过程中比典型的正种子更快地失去活力。在这项研究中，比较了在最佳条件下短时间（3 年）或长时间（20 年）储存的山毛榉种子，它们的发芽能力分别为 92%和 30%。
老化的种子显示出更高的膜损伤，表现为电解质泄漏和脂质过氧化水平的增加。分析基于胚胎轴，其中老化种子中含有更高水平的活性氧（ROS）和更高水平的蛋白质结合甲硫氨酸亚砜（MetO）。使用无标记定量蛋白质组学，鉴定了 3949 种蛋白质，其中 2442 种蛋白质可可靠地定量，表明在长期储存条件下，山毛榉种子中有 24 种更丰富的蛋白质和 35 种较少的蛋白质。基于基因本体注释的功能分析表明，核酸结合活性（分子功能）、核糖体组织或生物发生和跨膜运输（细胞过程）、翻译蛋白（蛋白类）和膜状解剖实体（细胞区室）受到了影响老化的山毛榉种子。为了验证蛋白质的氧化后翻译修饰甲硫氨酸亚砜（MetO）是否参与了山毛榉种子的老化，我们鉴定并定量了 226 种含有 MetO 的蛋白质，其中 9 种和 19 种在长期储存条件下的山毛榉种子中分别表现出明显的上调和下调的 MetO 水平。在山毛榉种子中鉴定并识别出几种 Msr 同工酶，分别为 MsrA1 样、MsrA4、MsrB5 和 MsrB5 样。只有 MsrA1 样在老化种子中的丰度降低。
我们证明，反映在膜蛋白丰度升高的膜完整性丧失对种子老化进程的影响大于 MetO/Msr 系统。蛋白质组学分析使我们能够提出蛋白质 Sec61 和甘油醛-3-磷酸脱氢酶作为山毛榉种子潜在的长寿调节剂。
