Table_2_Comparative Proteomics at the Critical Node of Vigor Loss in Wheat Seeds Differing in Storability.XLSX

The critical node (CN, 85% germination) of seed viability is an important threshold for seed regeneration decisions after long-term conservation. Dependent on the germplasm, the storage period until CN is reached varies and information on the divergence of the proteomic profiles is limited. Therefore, the study aims to identify key proteins and mechanisms relevant for a long plateau phase and a late CN during artificial seed aging of wheat. Seeds of the storage-tolerant genotype (ST) TRI 23248, and the storage-sensitive genotype (SS) TRI 10230 were exposed to artificial ageing (AA) and extracted embryos of imbibed seeds were analyzed using an iTRAQ-based proteomic technique. ST and SS required AA for 24 and 18 days to reach the CN, respectively. Fifty-seven and 165 differentially abundant proteins (DAPs) were observed in the control and aged groups, respectively. Interestingly, a higher activity in metabolic processes, protein synthesis, transcription, cell growth/division, and signal transduction were already found in imbibed embryos of control ST seeds. After AA, 132 and 64 DAPs were accumulated in imbibed embryos of both aged ST and SS seeds, respectively, which were mainly associated with cell defense, rescue, and metabolism. Moreover, 78 DAPs of ST appeared before CN and were mainly enriched in biological pathways related to the maintenance of redox and carbon homeostasis and they presented a stronger protein translation ability. In contrast, in SS, only 3 DAPs appeared before CN and were enriched only in the structural constituents of the cytoskeleton. In conclusion, a longer span of plateau phase might be obtained in seeds when proteins indicate an intense stress response before CN and include the effective maintenance of cellular homeostasis, and avoidance of excess accumulation of cytotoxic compounds. Although key proteins, inherent factors and the precise regulatory mechanisms need to be further investigated, the found proteins may also have functional potential roles during long-term seed conservation.

种子活力临界节点（CN，发芽率85%）是长期种子保存后制定更新决策的重要阈值。不同种质资源达到临界节点所需的储存时长存在差异，目前关于其蛋白质组谱差异的相关信息仍较为有限。为此，本研究旨在鉴定小麦人工种子老化过程中，与较长活力平台期及较晚出现的临界节点相关的关键蛋白及其作用机制。本研究选取耐储基因型（ST）TRI 23248与储存敏感基因型（SS）TRI 10230的种子进行人工老化（AA）处理，并采用基于同位素标记相对和绝对定量（iTRAQ）的蛋白质组学技术，对吸胀种子的提取胚进行分析。结果显示，ST与SS基因型种子分别需经过24天和18天的人工老化处理，方可达到临界节点。对照组与老化组样本中分别鉴定出57种和165种差异丰度蛋白（DAPs）。值得关注的是，未接受人工老化处理的ST基因型种子吸胀胚中，代谢过程、蛋白质合成、转录、细胞生长与分裂及信号转导通路的活性已处于较高水平。经人工老化处理后，ST与SS基因型老化种子的吸胀胚中分别累积得到132种和64种差异丰度蛋白，这些蛋白主要与细胞防御、修复及代谢过程相关。此外，ST基因型种子在达到临界节点前即出现78种差异丰度蛋白，主要富集于氧化还原稳态与碳稳态维持相关的生物学通路，且表现出更强的蛋白质翻译能力。与之相反，SS基因型种子仅在临界节点前出现3种差异丰度蛋白，且仅富集于细胞骨架结构组分相关通路。综上，若种子中的蛋白在临界节点前即呈现强烈的应激响应，并能有效维持细胞稳态、避免细胞毒性化合物过度积累，则可能拥有更长的活力平台期。尽管关键蛋白、内在调控因子及精确的调控机制仍需进一步研究，但本研究发现的蛋白或许在长期种子保存过程中具备潜在的功能作用。