Biosystems and Integrative Sciences Institute (BioISI), University of Tras-os-Montes and Alto Douro (UTAD), 5000-801, Vila Real, Portugal.
Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), University of de Tras-os-Montes and Alto Douro, Quinta de Prados, 5000-801, Vila Real, Portugal.
Protoplasma. 2019 May;256(3):763-775. doi: 10.1007/s00709-018-01335-1. Epub 2018 Dec 15.
Seed priming with iron (Fe) and/or zinc (Zn) can overcome the reduced availability of these micronutrients in soils and crops, but suitable dosages should be predetermined. Nucleolus responds to stress, such as cytotoxicity, with alterations perceivable by cytogenetic analyses. This work intends to study how seed priming with Fe and/or Zn affects the nucleolar activity in roots and the total soluble protein content in the flour of bread wheat cv. 'Jordão'. Seven priming treatments with 0 mg L to 8 mg L of Fe and/or Zn were performed. In all treatments, each metaphase cell presented a maximum of six nucleolar organizer regions positively stained with silver nitrate (Ag-NORs). Also, a maximum number of six nucleoli per nucleus were observed in all treatments, except in the hydroprimed seeds (used as control) that showed a maximum of five nucleoli, probably due to nucleolar fusion. Irregular interphases were frequent in treatments with the highest dosage of micronutrients (8 mg L Fe and/or 8 mg L Zn). The nucleolar area reduced (p < 0.001) as the number of nucleoli increased, and it was lower in treatments with a combination of Fe and Zn. However, the combinations of Fe and Zn showed the highest concentrations of total soluble protein (p ≤ 0.001). Although a reduced nucleolar area represents low ribosomal RNA gene transcription and ribosomal production, the significant increase of the number of nucleoli in the seeds primed with Fe and Zn enhanced the total soluble protein content as compared to the hydroprimed seeds (control) probably due to an increase of nucleolar surface-to-volume ratio that improved the protein synthesis. Overall, this work revealed that priming of bread wheat seeds with suited dosages of Fe and Zn can improve the nutritional value of flour, and the nucleolar number, morphology, and area can be useful biomarkers in cytotoxicity studies.
种子引发可以克服土壤和作物中这些微量营养素的可用性降低的问题，但应预先确定合适的剂量。核仁会对细胞毒性等应激做出反应，细胞遗传学分析可以观察到这些变化。本研究旨在研究用铁（Fe）和/或锌（Zn）对种子进行引发处理如何影响根的核仁活性和面包小麦 cv“Jordão”面粉中的总可溶性蛋白质含量。进行了七种用 0 mg L 到 8 mg L 的 Fe 和/或 Zn 进行引发处理的实验。在所有处理中，每个中期细胞的核仁组织区都最多被硝酸银（Ag-NORs）染成阳性 6 次。此外，在所有处理中，每个核仁最多有 6 个核仁，除了水引发的种子（用作对照），其最多有 5 个核仁，可能是由于核仁融合。在最高剂量的微量营养素处理中（8 mg L Fe 和/或 8 mg L Zn），不规则的间期很常见。核仁面积随着核仁数量的增加而减少（p < 0.001），且在同时含有 Fe 和 Zn 的处理中更小。然而，Fe 和 Zn 的组合表现出最高的总可溶性蛋白浓度（p ≤ 0.001）。虽然核仁面积的减少代表着核糖体 RNA 基因转录和核糖体合成减少，但在 Fe 和 Zn 引发的种子中，核仁数量的显著增加提高了面粉中的总可溶性蛋白含量，与水引发的种子（对照）相比，可能是由于核仁表面与体积比的增加，从而提高了蛋白质合成。总的来说，本研究表明，用适宜剂量的 Fe 和 Zn 对面包小麦种子进行引发处理可以提高面粉的营养价值，核仁的数量、形态和面积可以作为细胞毒性研究的有用生物标志物。
