ABSTRACT Methylglyoxal (MG), a cytotoxic oxygenated short aldehyde, is a by-product of various metabolic reactions in plants, including glycolysis. The basal level of MG in plants is low, whereby it acts as an essential signaling molecule regulating multiple cellular processes. However, hyperaccumulation of MG under stress conditions is detrimental for plants as it inhibits multiple developmental processes, including seed germination, photosynthesis, and root growth. The evolutionarily conserved glyoxalase system is critical for MG detoxification, and it comprises of two-enzymes, the glyoxalase-I and glyoxalase-II. Here, we report the functional characterization of six putative glyoxalase-I genes from date palm (Phoenix dactylifera L.) (PdGLX1), by studying their gene expression under various environmental stress conditions and investigating their function in bacteria (Escherichia coli) and yeast (Saccharomyces cerevisiae) mutant cells. The putative PdGLX1 genes were initially identified using computational methods and cloned using molecular tools. The PdGLX1 gene expression analysis using quantitative PCR (qPCR) revealed differential expression under various stress conditions such as salinity, oxidative stress, and exogenous MG stress in a tissue-specific manner. Further, in vivo functional characterization indicated that overexpression of the putative PdGLX1 genes in E. coli enhanced their growth and MG detoxification ability. The putative PdGLX1 genes were also able to complement the loss-of-function MG hypersensitive GLO1 (YML004C) yeast mutants and promote growth by enhancing MG detoxification and reducing the accumulation of reactive oxygen species (ROS) under stress conditions as indicated by flow cytometry. These findings denote the potential importance of PdGLX1 genes in MG detoxification under stress conditions in the date palm.

中文翻译：

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非生物胁迫下椰枣中乙二醛酶-I（PdGLX1）基因家族的功能表征

摘要 甲基乙二醛 (MG) 是一种具有细胞毒性的含氧短醛，是植物中各种代谢反应（包括糖酵解）的副产物。植物中 MG 的基础水平较低，因此它充当调节多个细胞过程的重要信号分子。然而，在胁迫条件下 MG 的过度积累对植物有害，因为它会抑制多种发育过程，包括种子萌发、光合作用和根生长。进化上保守的乙二醛酶系统对 MG 解毒至关重要，它由两种酶组成，即乙二醛酶-I 和乙二醛酶-II。在这里，我们报告了来自枣椰树 (Phoenix dactylifera L.) (PdGLX1) 的六个假定的乙二醛酶-I 基因的功能特征，通过研究它们在各种环境胁迫条件下的基因表达并研究它们在细菌（大肠杆菌）和酵母（酿酒酵母）突变细胞中的功能。假定的 PdGLX1 基因最初是使用计算方法鉴定的，并使用分子工具进行克隆。使用定量 PCR (qPCR) 进行的 PdGLX1 基因表达分析揭示了在各种胁迫条件下（如盐度、氧化胁迫和外源性 MG 胁迫以组织特异性方式）的差异表达。此外，体内功能表征表明，大肠杆菌中推定的 PdGLX1 基因的过表达增强了它们的生长和 MG 解毒能力。假定的 PdGLX1 基因还能够补充功能丧失的 MG 过敏 GLO1 (YML004C) 酵母突变体，并通过增强 MG 解毒和减少应激条件下活性氧 (ROS) 的积累来促进生长，如流式细胞术所示。这些发现表明 PdGLX1 基因在枣椰树胁迫条件下 MG 解毒中的潜在重要性。