Glucose-6-phosphate dehydrogenase (G6PDH), as a key enzyme in the pentose phosphate pathway, extensively responds to the biotic and abiotic stresses. In this study we focussed on the G6PDH role in the alleviation of alkaline stress induced by silicon (Si) in highland barley. Application of Si reduced the water loss and malondialdehyde (MDA) and reactive oxygen species (ROS) contents, improved the fresh weight, photosynthesis, K⁺ content, and the superoxide dismutase (SOD) and catalase (CAT) activities, thus alleviating the damage caused by alkaline stress. The G6PDH activity, especially the cytoplasmic G6PDH, significantly increased under alkaline stress, and was further stimulated by the addition of exogenous Si. Meanwhile, the levels of NADPH and reduced glutathione (GSH) showed similar profiles to G6PDH activity under NaHCO₃ and NaHCO₃ + Si treatments. The inhibition of G6PDH activity by glucosamine abolished the relieving effect of Si on alkaline stress, which was manifested in the increase of ROS and the decrease of GSH content. Together, our results suggest that Si-enhanced tolerance of alkaline stress may be related to the regulation of GSH levels by the cytoplasmic G6PDH in highland barley.

6-磷酸葡萄糖脱氢酶（G6PDH）作为磷酸戊糖途径中的关键酶，广泛响应生物和非生物胁迫。在这项研究中，我们集中于G6PDH在减轻高地大麦中硅（Si）诱导的碱性胁迫中的作用。硅的施用减少了水分损失和丙二醛（MDA）和活性氧（ROS）含量，提高了鲜重，光合作用，K ⁺含量以及超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性，从而减轻了碱性胁迫造成的破坏。G6PDH活性，尤其是细胞质G6PDH，在碱性胁迫下显着增加，并通过添加外源Si进一步刺激。同时，在NaHCO ₃和NaHCO ₃ + Si处理下，NADPH和还原型谷胱甘肽（GSH）的水平与G6PDH活性相似。氨基葡萄糖对G6PDH活性的抑制作用消除了Si对碱胁迫的缓解作用，这表现为ROS的增加和GSH含量的减少。总之，我们的结果表明，硅对碱胁迫的耐受性可能与高地大麦中细胞质G6PDH对GSH水平的调节有关。