Identification and expression dynamics of three WUSCHEL related homeobox 13 (WOX13) genes in peanut.

WUSCHEL-related homeobox (WOX) genes play key roles in plant stem cell maintenance and development. WOX genes showed specific expression patterns which are important for their functions. WOX13 subfamily genes as the ancestor genes of this family were less studied in the past. In this study, we cloned three Arachis hypogaea (peanut) WOX13 (AhWOX13) subfamily genes from peanut: WOX13A and WOX13B1, 2. WOX13B1 encoded a same protein as WOX13B2, and there were only two-base difference between these two genes. Differential expression patterns were observed for these three AhWOX13 subfamily genes in different tissues and developmental stages. Phylogenic trees analysis showed that these AhWOX13 subfamily genes were the most conserved WOX genes and belonged to the ancient clade of WOX family. This was also supported by the conserved motif analysis. Selective pressure analysis showed that the WOX family genes mainly underwent weak purifying selection (ω = 0.58097), while many positive mutations accumulated during the evolution history. Under the purifying selection, gene duplication event and loss of duplicated gene play important roles in the expansion and evolution of WOX family.