Methylglyoxal (MG), a by-product of various metabolic processes, including glycolysis, is a highly reactive cytotoxic metabolite. The level of MG in the cell is maintained at a non-toxic level via MG detoxification pathways such as the universal glyoxalase system, including glyoxalase I/II/III enzymes. Glyoxalase III (DJ-1) can breakdown MG to D-lactate in a single step without reducing glutathione (GSH). Elucidating the function of the DJ-1 gene family may provide further knowledge about its role in plants under abiotic stresses. Here, we characterize four glyoxalase III genes (PdDJ-1B1, PdDJ-1B2, PdDJ-1C, and PdDJ-1D) encoding the conserved DJ-1 domain in the genome of the date palm, a crop with high drought and salinity tolerance. The expression level of the PdDJ-1 genes increased in date palm leaves upon salinity treatment. In addition, overexpression of PdDJ-1 genes in Escherichia coli and the complementation in yeast hsp31Δ knockout mutant cells enhanced their growth rate and reduced the accumulation of reactive oxygen species (ROS) under MG and oxidative stress conditions as shown by the flow cytometry assay. Subcellular localization using confocal microscopy revealed the accumulation of PdDJ-1B1, PdDJ-1C, and PdDJ-1D in the chloroplast, whereas PdDJ-1B2 was localized to the cytosol. Remarkably, constitutive expression of the PdDJ-1C gene in Arabidopsis thaliana Columbia (Col-0) resulted in the generation of non-viable albino plants implying that PdDJ-1C plays a critical function in chloroplast development. These findings suggest that PdDJ-1 protein has an important function in MG-detoxification and maintaining the redox balance in date palm plants under abiotic stress conditions.

中文翻译：

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在非生物胁迫下生长的枣椰树中乙二醛酶III基因的功能表征和表达谱

甲基乙二醛 (MG) 是各种代谢过程（包括糖酵解）的副产物，是一种高度反应性的细胞毒性代谢物。细胞中的 MG 水平通过 MG 解毒途径（例如通用乙二醛酶系统，包括乙二醛酶 I/II/III 酶）维持在无毒水平。乙二醛酶 III (DJ-1) 可以在一个步骤中将 MG 分解为 D-乳酸，而不会还原谷胱甘肽 (GSH)。阐明 DJ-1 基因家族的功能可以进一步了解其在非生物胁迫下植物中的作用。在这里，我们描述了在枣椰树基因组中编码保守 DJ-1 结构域的四个乙二醛酶 III 基因（PdDJ-1B1、PdDJ-1B2、PdDJ-1C 和 PdDJ-1D），这是一种具有高干旱和耐盐性的作物。PdDJ-1 基因在海枣叶中的表达水平在盐分处理后增加。此外，如流式细胞术测定所示，在 MG 和氧化应激条件下，大肠杆菌中 PdDJ-1 基因的过表达和酵母 hsp31Δ 敲除突变细胞中的互补提高了它们的生长速率并减少了活性氧 (ROS) 的积累。使用共聚焦显微镜的亚细胞定位显示 PdDJ-1B1、PdDJ-1C 和 PdDJ-1D 在叶绿体中的积累，而 PdDJ-1B2 定位于细胞质。值得注意的是，PdDJ-1C 基因在拟南芥哥伦比亚 (Col-0) 中的组成型表达导致了无法存活的白化病植物的产生，这意味着 PdDJ-1C 在叶绿体发育中起关键作用。