| Summary: | Abiotic stresses such as high temperature, high humidity, and heavy metals are important factors that affect seed development and quality, and restrict yield in soybean. The ATX1-type copper chaperones are an important type of proteins that are used for maintaining intracellular copper ion homeostasis. In our previous study, a copper chaperone protein <i>GmATX1</i> was identified in developing seeds of soybean under high temperature and humidity (HTH) stresses. In this study, the <i><i>GmATX1</i></i> gene was isolated, and multiple alignment analysis showed that its encoding protein shared high sequence identities with other plant orthologues of copper chaperone proteins containing the HMA domain, and a conserved metal ion-binding site, CXXC. A subcellular localization assay indicated that <i>GmATX1</i> was localized in the cell membrane and nucleus. An expression analysis indicated that <i><i>GmATX1</i></i> was involved in seed development, and in response to HTH and heavy metal stresses in soybean. <i><i>GmATX1</i></i>-silent soybean seedlings were found to be more severely damaged than the control under HTH stress. Moreover, the silencing of <i><i>GmATX1</i></i> reduced antioxidase activity and reactive oxygen species (ROS) scavenging ability in the seedling leaves. The overexpression of <i><i>GmATX1</i></i> in <i>Arabidopsis</i> improved seed vigor and seedling tolerance, and enhanced antioxidase activity and ROS scavenging ability under HTH and heavy metal stresses. Our results indicated that <i><i>GmATX1</i></i> could promote seed vigor and seedling tolerance to HTH and heavy metal stresses in transgenic <i>Arabidopsis</i>, and this promotion could be achieved by enhancing the antioxidase activity and ROS scavenging ability.
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