Abstract

WUSCHEL-related homeobox (WOX) transcription factors (TFs) are well known for their role in plant development but are rarely studied in citrus. In this study, we identified 11 putative genes from the sweet orange genome and divided the citrusWOXgenes into three clades (modern/WUSCHEL(WUS), intermediate, and ancient). Subsequently, we performed syntenic relationship, intron-exon organization, motif composition, andcis-element analysis. Co-expression analysis based on RNA-seq and tissue-specific expression patterns revealed thatCsWOXgene expression has multiple intrinsic functions.CsWUShomolog ofAtWUSfunctions as a transcriptional activator and binds to specific DNA. Overexpression ofCsWUSin tobacco revealed dramatic phenotypic changes, including malformed leaves and reduced gynoecia with no seed development. Silencing ofCsWUSin lemon using the virus-induced gene silencing (VIGS) system implied the involvement ofCsWUSin cells of the plant stem. In addition, CsWUS was found to interact with CsCYCD3, an ortholog inArabidopsis(AtCYCD3,1). Yeast one-hybrid screening and dual luciferase activity revealed that two TFs (CsRAP2.12andCsHB22) bind to the promoter ofCsWUSand regulate its expression. Altogether, these results extend our knowledge of theWOXgene family along withCsWUSfunction and provide valuable findings for future study on development regulation and comprehensive data ofWOXmembers in citrus.Keywords:Citrus sinensis;CsWOXs;transcription factor;CsWUS