Identification of the SAUR Members in Woodland Strawberry (Fragaria vesca) and Detection of Their Expression Profiles in Response to Auxin Signals

The <i>SAUR</i> (Small Auxin-Upregulated RNA) family members are important early auxin responsive genes in plants, playing a key regulatory role in the auxin metabolism, signal transduction, plant organ development, and abiotic stress response. Auxin signaling is also crucial for strawberry fruit development, but its specific regulatory mechanism remains unclear. In this study, bioinformatics methods were used to systematically identify and evaluate the <i>FvSAUR</i> gene family members associated with the auxin signaling in strawberry. The woodland strawberry Yellow Wonder line 'YW5AF7' was used as the material to further investigate the expressional characteristics of <i>FvSAUR</i> members in response to the auxin signals. A total of 64 members of the <i>SAUR</i> gene family were identified in the woodland strawberry genome, associated with <i>FvSAUR1-64</i>. Further bioinformatics analysis revealed that the <i>FvSAUR</i> members have undergone significant structural differentiation during evolution, and their encoded proteins exhibit diversity in folding stability, physicochemical properties, and other aspects. The prediction of the cis-elements in the promoter sequences of these genes suggests that the <i>FvSAUR</i> genes may mediate multiple hormonal and environmental signals, participating in a wide range of biological processes. RNA seq data analysis combined with RT-qPCR analysis revealed a dynamic spatiotemporal expression pattern of the <i>FvSAUR</i> genes in the vegetative and reproductive organs of strawberries, particularly the high expression levels of <i>FvSAUR11</i>, <i>17</i>, <i>19</i>, <i>21</i>, and other genes in flowers and young fruits, suggesting their potential regulatory roles in strawberry fruit development. Exogenous auxin treatment experiments further suggested that the expression of <i>FvSAUR11</i> and <i>FvSAUR19</i> is sensitive to the changes in auxin levels, indicating their potential involvement in auxin signal transduction during strawberry fruit development. Subcellular localization results showed that both proteins are located in the nucleus. The results of this study systematically analyzed the sequence structure characteristics, evolutionary history, expression patterns, and potential functions of the strawberry <i>FvSAUR</i> family members, providing important insights for further elucidating the roles of <i>FvSAUR</i> genes in strawberry fruit growth and development.