Abstract: [Objective] WOX13 gene is a member of the ancient clade of the transcription factor of WOX (WUSCHEL related homeobox),which is mainly involved in the regulation of floral transition and root development. In this study,the expression patterns and overexpression phenotypic traits in Arabidopsis thaliana were analyzed to explore the gene function of CpWOX13 and also to provide a basis for comprehensive research on the mechanism of WOX13 genes in different species with low phylogenetic status.[Method] Based on the RNA-seq analysis at three different developmental stages (petal appears,flowering peak and declining) in Chimonanthus praecox ‘grandiflorus’,CpWOX13 gene was obtained by Reverse Transcription Polymerase Chain Reaction (RT-PCR). Phylogenetic tree was constructed by Neighbor-joining (NJ) method. CpWOX13 expression analysis in flower bud in April,May,July and September (4FB, 5FB, 7FB, 9FB) was carried out using quantitative real-time RT-PCR (qRT-PCR). The genetic effects of CpWOX13 on plant development were explored by studying the phenotypes, including rosette leaves,length of axial and lateral root and plant height between the 35S∷CpWOX13/Col-0 Arabidopsis lines and the wild type.Relative gene expression of CpWOX13 and endogenous gene from Arabidopsis was also carried out in three overexpression lines and WT by qRT-PCR.[Result] CpWOX13 clustered closely to WOX13 in Vitis vinifera and Arabidopsis, belonging to ancient clade of WUS family. qRT-PCR indicated that CpWOX13 transcripts were found at different developmental stages,4FB,5FB,7FB and 9FB.The highest CpWOX13 expression was observed in 5FB, nearly 6.5-fold higher than that of 4FB,and about 3.8-and 3.3-fold of 7FB and 9FB,respectively. Phenotypes were observed in different 35S∷CpWOX13/Col-0 lines compared with the Col-0. 35S∷CpWOX13 overexpression (OE) lines (OE6#,OE3# and OE8#)induced early flowering,in which the number of rosette leaves was slightly less than that of Arabidopsis Col-0. In addition,the length of axial root and the number of lateral root of transgenic lines increased significantly,the plant height was much higher than that of the wild type,with a maximum of 12 cm.[Conclusion] CpWOX13,one of the WOX family homologous genes,expressed in different developmental stages of C. praecox. The highest expression was detected in flower bud during the differentiation of stamen and pistil primordia in May.Overexpression of CpWOX13 affects the development of lateral root and results in early flowering in transgenic Arabidopsis.

Key words: Chimonanthus praecox, CpWOX13 gene, flower development, early flowering, functional analysis