| Summary: | Annexins are a superfamily of soluble calcium-dependent phospholipid-binding proteins that have considerable regulatory effects in plants, especially in response to adversity and stress. The <i>Arabidopsis thaliana AtAnn1</i> gene has been reported to play a significant role in various abiotic stress responses. In our study, the cDNA of an annexin gene highly similar to <i>AtAnn1</i> was isolated from the cassava genome and named <i>MeAnn2</i>. It contains domains specific to annexins, including four annexin repeat sequences (I–IV), a Ca<sup>2+</sup>-binding sequence, Ca<sup>2+</sup>-independent membrane-binding-related tryptophan residues, and a salt bridge-related domain. <i>MeAnn2</i> is localized in the cell membrane and cytoplasm, and it was found to be preferentially expressed in the storage roots of cassava. The overexpression of <i>MeAnn2</i> reduced the sensitivity of transgenic <i>Arabidopsis</i> to various Ca<sup>2+</sup>, NaCl, and indole-3-acetic acid (IAA) concentrations. The expression of the stress resistance-related gene <i>AtRD29B</i> and auxin signaling pathway-related genes <i>AtIAA4</i> and <i>AtLBD18</i> in transgenic <i>Arabidopsis</i> was significantly increased under salt stress, while the Malondialdehyde (MDA) content was significantly lower than that of the control. These results indicate that the <i>MeAnn2</i> gene may increase the salt tolerance of transgenic <i>Arabidopsis</i> via the IAA signaling pathway.
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