Gerna Davide, Roach Thomas, Stöggl Wolfgang, Wagner Johanna, Vaccino Patrizia, Limonta Margherita, Kranner Ilse
a Department of Botany , Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , Innsbruck , Austria.
b Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria , Research Unit for Cereal Selection in Continental Areas, S . Angelo Lodigiano , Italy.
Free Radic Res. 2017 Jun;51(6):568-581. doi: 10.1080/10715762.2017.1338344. Epub 2017 Jun 26.
The tripeptide antioxidant glutathione (γ-l-glutamyl-l-cysteinyl-glycine; GSH) essentially contributes to thiol-disulphide conversions, which are involved in the control of seed development, germination, and seedling establishment. However, the relative contribution of GSH metabolism in different seed structures is not fully understood. We studied the GSH/glutathione disulphide (GSSG) redox couple and associated low-molecular-weight (LMW) thiols and disulphides related to GSH metabolism in bread wheat (Triticum aestivum L.) seeds, focussing on redox changes in the embryo and endosperm during germination. In dry seeds, GSH was the predominant LMW thiol and, 15 h after the onset of imbibition, embryos of non-germinated seeds contained 12 times more LMW thiols than the endosperm. In germinated seeds, the embryo contained 17 and 11 times more LMW thiols than the endosperm after 15 and 48 h, respectively. This resulted in the embryo having significantly more reducing half-cell reduction potentials of GSH/GSSG and cysteine (Cys)/cystine (CySS) redox couples (E and E, respectively). Upon seed germination and early seedling growth, Cys and CySS concentrations significantly increased in both embryo and endosperm, progressively contributing to the cellular LMW thiol-disulphide redox environment (E). The changes in E could be related to the mobilisation of storage proteins in the endosperm during early seedling growth. We suggest that E and E can be used as markers of the physiological and developmental stage of embryo and endosperm. We also present a model of interaction between LMW thiols and disulphides with hydrogen peroxide (HO) in redox regulation of bread wheat germination and early seedling growth.
三肽抗氧化剂谷胱甘肽（γ-L-谷氨酰-L-半胱氨酰-甘氨酸；GSH）对硫醇-二硫键的转化起着重要作用，而硫醇-二硫键的转化参与种子发育、萌发和幼苗形成的调控。然而，谷胱甘肽代谢在不同种子结构中的相对作用尚未完全明确。我们研究了面包小麦（Triticum aestivum L.）种子中谷胱甘肽/谷胱甘肽二硫化物（GSSG）氧化还原对以及与谷胱甘肽代谢相关的低分子量（LMW）硫醇和二硫化物，重点关注萌发过程中胚和胚乳的氧化还原变化。在干燥种子中，谷胱甘肽是主要的低分子量硫醇，吸胀开始15小时后，未萌发种子的胚中低分子量硫醇含量比胚乳多12倍。在萌发种子中，15小时和48小时后，胚中低分子量硫醇含量分别比胚乳多17倍和11倍。这导致胚中谷胱甘肽/谷胱甘肽二硫化物和半胱氨酸（Cys）/胱氨酸（CySS）氧化还原对的还原半电池还原电位（分别为E和E）明显更高。种子萌发和幼苗早期生长时，胚和胚乳中的半胱氨酸和胱氨酸浓度均显著增加，逐渐影响细胞内低分子量硫醇-二硫键氧化还原环境（E）。E的变化可能与幼苗早期生长过程中胚乳中贮藏蛋白的动员有关。我们认为E和E可作为胚和胚乳生理及发育阶段的标志物。我们还提出了一个低分子量硫醇和二硫化物与过氧化氢（HO）在面包小麦萌发和幼苗早期生长的氧化还原调控中相互作用的模型。
