Identification and functional characterization of the <i>Aux/IAA</i> gene <i>VcIAA27</i> in blueberry

<i>Aux/IAA</i> genes are an important class of players in diverse developmental processes in plants, which generally exert their functions through the auxin signaling pathway. Blueberry is an economically and nutritionally important berry-bearing crop. However, <i>Aux/IAA</i> genes remain unknown in blueberry. In the present study, an <i>Aux/IAA</i> gene (<i>VcIAA27</i>) was identified and characterized in blueberry, and it is most closely related to IAA27 in other plant species. Expression analysis indicated that <i>VcIAA27</i> transcripts accumulate highly in shoot, flower and fruit. Interestingly, <i>VcIAA27</i> was highly expressed at early fruit developmental stages, and dramatically decreased from the onset of fruit ripening, implying that <i>VcIAA27</i> possibly plays important roles during fruit enlargement. Meanwhile, the analysis of promoter activity in Arabidopsis showed that strong GUS signal was detected in the trichome and hydathodes of leaves, receptacle of silique, and lateral roots of seedling. Overexpression of <i>VcIAA27</i> in Arabidopsis leads to auxin-related defects such as downward-curled leaves, short or sterile siliques, shorter stature, and more shoot branches. Moreover, qPCR analysis indicated that <i>VcIAA27</i> is able to alter the expression patterns of the auxin-related genes <i>BRU6, SAG13, SAUR26</i> in Arabidopsis, suggesting that <i>VcIAA27</i> might be negatively involved in the auxin signaling pathway. The findings will greatly contribute to future investigation of <i>Aux/IAA</i>-mediated mechanisms that control blueberry development, especially fruit development and ripening.