Identification of the WUSCHEL-Related Homeobox (WOX) Gene Family, and Interaction and Functional Analysis of TaWOX9 and TaWUS in Wheat

Abstract

The WUSCHEL-related homeobox (WOX) is a family of plant-specific transcription factors, with important functions, such as regulating the dynamic balance of division and differentiation of plant stem cells and plant organ development. We identified 14 distinct <i>TaWOX</i> genes in the wheat (Triticum aestivum L.) genome, based on a genome-wide scan approach. All of the genes under evaluation had positional homoeologs on subgenomes A, B and D except TaWUS and TaWOX14. Both <i>Ta</i>WOX<i>14a</i> and <i>Ta</i>WOX<i>14</i>d had a paralogous copy on the same genome due to tandem duplication events. A phylogenetic analysis revealed that <i>TaWOX</i> genes could be divided into three groups. We performed functional characterization of <i>TaWOX</i> genes based on the evolutionary relationships among the <i>WOX</i> gene families of wheat, rice (Oryza sativa L.), and <i>Arabidopsis.</i> An overexpression analysis of <i>TaWUS</i> in <i>Arabidopsis</i> revealed that it affected the development of outer floral whorl organs. The overexpression analysis of <i>TaWOX9</i> in <i>Arabidopsis</i> revealed that it promoted the root development. In addition, we identified some interaction between the TaWUS and TaWOX9 proteins by screening wheat cDNA expression libraries, which informed directions for further research to determine the functions of TaWUS and TaWOX9. This study represents the first comprehensive data on members of the WOX gene family in wheat.