Wang Chun-Chin, Penfield Steven, Moger Julian
Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK.
Department of Crop Genetics, John Innes Centre, Norwich, NR4 7UH, UK.
Analyst. 2025 Jan 27;150(3):498-504. doi: 10.1039/d4an01409j.
The seed coat plays a pivotal role in seed development and germination, acting as a protective barrier and mediating interac-tions with the external environment. Traditional histochemical techniques and analytical methods have provided valuable insights into seed coat composition and function. However, these methods often suffer from limitations such as indirect chemical signatures and lack of spatial resolution. Here, we introduce stimulated Raman scattering (SRS) microscopy as a novel analytical tool for non-destructive, label-free, high-resolution mapping of biopolymers, water and applied active ingre-dients (AIs) in intact seed coats. We demonstrate the capability of SRS microscopy to perform depth-resolved, chemically selective imaging of major seed coat biopolymers (pectin, tannin, and suberin). By comparing wild type arabidopsis thali-ana seeds with genetically modified mutants deficient in suberin and tannin, we illustrate the potential for semi-quantitative analysis of biopolymer content. Furthermore, we show that SRS microscopy can track the permeability of seed coats to wa-ter using deuterated water (DO) uptake studies. Real-time imaging reveals differences in water permeation between wild type and suberin deficient seeds, highlighting the importance of seed coat composition in regulating water uptake during germina-tion. Additionally, we extend the application of SRS microscopy to large seeds, such as brassica oleracea, utilizing -detected imaging for surface studies. Finally, using a deuterated insecticide (clothianidin-d3), we demonstrate the capability of SRS microscopy to visualize the incorporation of AIs into seed coats. Our study presents SRS microscopy as a powerful tool for characterizing seed coat composition and understanding the diffusion of low molecular weight compounds into seeds. This technique offers new opportunities for designing seeds with tailored properties for improved germination and resilience to environmental stressors.
种皮在种子发育和萌发过程中起着关键作用，它作为一道保护屏障，并介导与外部环境的相互作用。传统的组织化学技术和分析方法为种皮的组成和功能提供了有价值的见解。然而，这些方法常常存在局限性，比如化学特征间接以及缺乏空间分辨率。在此，我们引入受激拉曼散射（SRS）显微镜作为一种新型分析工具，用于对完整种皮中的生物聚合物、水和应用的活性成分（AIs）进行无损、无标记的高分辨率成像。我们展示了SRS显微镜对种皮主要生物聚合物（果胶、单宁和木栓质）进行深度分辨、化学选择性成像的能力。通过将野生型拟南芥种子与缺乏木栓质和单宁的转基因突变体进行比较，我们阐述了生物聚合物含量半定量分析的潜力。此外，我们表明SRS显微镜可以通过氘代水（D₂O）吸收研究追踪种皮对水的渗透性。实时成像揭示了野生型和缺乏木栓质种子之间水分渗透的差异，突出了种皮组成在调节种子萌发期间水分吸收中的重要性。此外，我们将SRS显微镜的应用扩展到大型种子，如甘蓝，利用 -检测成像进行表面研究。最后，使用氘代杀虫剂（噻虫胺-d₃），我们展示了SRS显微镜可视化活性成分掺入种皮的能力。我们的研究表明SRS显微镜是一种用于表征种皮组成和理解低分子量化合物向种子扩散的强大工具。这项技术为设计具有定制特性以改善萌发和抵御环境胁迫能力的种子提供了新机会。
