Institute of Dendrology, Polish Academy of Sciences, Kórnik, 62-035, Poland.
Institute of Dendrology, Polish Academy of Sciences, Kórnik, 62-035, Poland.
J Plant Physiol. 2018 Apr;223:72-83. doi: 10.1016/j.jplph.2018.02.010. Epub 2018 Mar 8.
Approximately 20% of plant species, including silver maple (Acer saccharinum L.), produce seeds that are sensitive to desiccation, which is reflected in their poor storage potential and viability. In the search for a compound that can improve seed recalcitrance, freshly harvested seeds were soaked in either 2.5 mM reduced glutathione (GSH) or water and desiccated to comparable water levels of 55-20%. We examined the impact of a doubled endogenous level of glutathione on the seed germination capacity, the activity of enzymes involved in glutathione metabolism, the cell membrane components and integrity, reactive oxygen species, and ascorbate levels. GSH treatment resulted in slower dehydration and a higher germination capacity. The increased glutathione was mainly consumed by glutathione S-transferase, leading to more efficient detoxification, and by dehydroascorbate reductase (DHAR), accelerating the ascorbate regeneration. As a result, the cellular environment became more reduced, and protection of the membrane structures was enhanced. The ameliorated membrane integrity was manifested via a lower electrolyte leakage and a lower lipid peroxide level despite the higher level of hydrogen peroxide (HO) detected in the GSH-treated seeds. The degradation of phospholipids (PLs) was less intense and related to the phosphatidylinositol (PI) level, which is the precursor of the phospholipase D cofactor, whereas in water-soaked seeds, PL degradation was promoted by HO. The germination capacity of the dehydrated seeds depended primarily on the level of HO, lipid hydroxyperoxides, electrolyte leakage, GSH, the half-cell reduction potential of glutathione, PI, and the activity of DHAR and γ-glutamylcysteine synthetase. Interestingly, HO affected all of the parameters. The germination of GSH-boosted seeds was strongly impacted by the pool of ascorbate, the half-cell reduction potential of ascorbate, and the glutathione peroxidase activity. In general, germination was DHAR activity-dependent. A strong negative correlation was detected in the water-soaked seeds, whereas a strong positive correlation was detected in the GSH-treated seeds. The enhanced level of glutathione likely improved the efficiency of the ascorbate-glutathione cycle, confirming its effect on seed germinability after dehydration.
大约 20%的植物物种，包括银枫（Acer saccharinum L.），其种子对干燥敏感，这反映在它们较差的储存潜力和活力上。在寻找一种可以提高种子抗逆性的化合物的过程中，我们将新鲜收获的种子浸泡在 2.5mM 还原型谷胱甘肽（GSH）或水中，并将其干燥至 55-20%的可比水分水平。我们研究了谷胱甘肽内源性水平加倍对种子发芽能力、谷胱甘肽代谢相关酶活性、细胞膜成分和完整性、活性氧（ROS）和抗坏血酸水平的影响。GSH 处理导致种子脱水速度较慢，发芽能力提高。增加的谷胱甘肽主要被谷胱甘肽 S-转移酶消耗，从而更有效地解毒，也被脱氢抗坏血酸还原酶（DHAR）消耗，从而加速抗坏血酸的再生。结果，细胞环境变得更还原，膜结构的保护得到增强。尽管在 GSH 处理的种子中检测到更高水平的过氧化氢（HO），但改良的膜完整性通过更低的电解质泄漏和更低的脂质过氧化物水平表现出来。磷脂（PL）的降解程度较轻，与磷脂酶 D 辅因子的前体磷脂酰肌醇（PI）水平有关，而在水浸泡的种子中，PL 降解是由 HO 促进的。脱水种子的发芽能力主要取决于 HO、脂质过氧化物、电解质泄漏、GSH、谷胱甘肽的半细胞还原电势、PI 和 DHAR 和γ-谷氨酰半胱氨酸合成酶的活性。有趣的是，HO 影响了所有参数。GSH 增强种子的发芽受抗坏血酸池、抗坏血酸的半细胞还原电势和谷胱甘肽过氧化物酶活性的强烈影响。总的来说，发芽依赖于 DHAR 活性。在水浸泡的种子中检测到强烈的负相关，而在 GSH 处理的种子中检测到强烈的正相关。谷胱甘肽水平的提高可能提高了抗坏血酸-谷胱甘肽循环的效率，证实了其对脱水后种子发芽能力的影响。
