Institute of Plant Sciences, University of Graz, Schubertstrasse 51, 8010, Graz, Austria.
Protoplasma. 2010 Oct;246(1-4):15-24. doi: 10.1007/s00709-010-0111-2. Epub 2010 Feb 26.
This study describes the subcellular distribution of glutathione in roots and leaves of different plant species (Arabidopsis, Cucurbita, and Nicotiana). Glutathione is an important antioxidant and redox buffer which is involved in many metabolic processes including plant defense. Thus information on the subcellular distribution in these model plants especially during stress situations provides a deeper insight into compartment specific defense reactions and reflects the occurrence of compartment specific oxidative stress. With immunogold cytochemistry and computer-supported transmission electron microscopy glutathione could be localized in highest contents in mitochondria, followed by nuclei, peroxisomes, the cytosol, and plastids. Within chloroplasts and mitochondria, glutathione was restricted to the stroma and matrix, respectively, and did not occur in the lumen of cristae and thylakoids. Glutathione was also found at the membrane and in the lumen of the endoplasmic reticulum. It was also associated with the trans and cis side of dictyosomes. None or only very little glutathione was detected in vacuoles and the apoplast of mesophyll and root cells. Additionally, glutathione was found in all cell compartments of phloem vessels, vascular parenchyma cells (including vacuoles) but was absent in xylem vessels. The specificity of this method was supported by the reduction of glutathione labeling in all cell compartments (up to 98%) of the glutathione-deficient Arabidopsis thaliana rml1 mutant. Additionally, we found a similar distribution of glutathione in samples after conventional fixation and rapid microwave-supported fixation. Thus, indicating that a redistribution of glutathione does not occur during sample preparation. Summing up, this study gives a detailed insight into the subcellular distribution of glutathione in plants and presents solid evidence for the accuracy and specificity of the applied method.
本研究描述了不同植物物种（拟南芥、南瓜和烟草）的根和叶中谷胱甘肽的亚细胞分布。谷胱甘肽是一种重要的抗氧化剂和氧化还原缓冲剂，参与包括植物防御在内的许多代谢过程。因此，这些模式植物中谷胱甘肽亚细胞分布的信息，特别是在应激情况下，提供了对特定隔室防御反应的更深入了解，并反映了特定隔室氧化应激的发生。通过免疫金细胞化学和计算机支持的透射电子显微镜，谷胱甘肽可以在线粒体中以最高含量定位，其次是核、过氧化物酶体、细胞质和质体。在线粒体和叶绿体中，谷胱甘肽分别局限于基质和基质，而不在嵴和类囊体的腔中。谷胱甘肽也存在于内质网膜和腔中。它还与高尔基复合体的顺面和反面相关。在液泡和质膜外质体中未检测到或仅检测到少量谷胱甘肽。在韧皮部导管的所有细胞隔室中都发现了谷胱甘肽，血管薄壁细胞（包括液泡），但在木质部导管中不存在。该方法的特异性得到了谷胱甘肽缺乏型拟南芥 rml1 突变体中所有细胞隔室（高达 98%）中谷胱甘肽标记减少的支持。此外，我们还发现传统固定和快速微波支持固定后样品中谷胱甘肽的分布相似。因此，表明在样品制备过程中不会发生谷胱甘肽的再分布。总之，本研究深入了解了植物中谷胱甘肽的亚细胞分布，并为所应用方法的准确性和特异性提供了确凿证据。
