Evolutionary And Functional Analysis Of WUSCHEL-related Homeobox Family Of Moso Bamboo

Meristem maintenance and differentiation determine the growth and development of plants.Moso bamboo(Phyllostachys edulis)is one of the most important economic bamboo species with both of economic and ecological benefits in China.At present,the study of bamboo flowering and clonal regeneration is difficult,and has become a attention-getting focus.The formation,maintenance and development of the primary meristem and secondary meristem are the critical basis for plant distinctive tissues.WOX family has been reported as an important regulatory factor in plant morphogenesis.It is of great theoretical and practical significance to excavate the potential functions of WOX in regulating meristem development.In this study,the evolutionary relationship and functional differentiation of WOX genes were studied among plant kingdom.The Bambusoideae WOX gene duplications events were analyzed by studying the herbaceous and woody bamboos with different ploidy.The expression patterns of certain WOXs were studied in the representative meristem tissues of moso bamboo to screen WOXs related to the development of apical meristem,lateral meristem and flower meristem.The protein factors interacting with WOX proteins were initially screened by Yeast Two-hybrid Assay.Functions of WOXs were preliminarily verified by transgenic rice.1.In this study,12 OlaWOXs,9 RguWOX,18 GanWOXs,27 PheWOXs,and 26 BamWOXs were identified and categorized into ancient,intermediate,and WUS clades.The evolution of the WOX family is subject to intense purification selection among plant kingdom.The segmental duplications and polyploidy are the major driver of the expansion of the bamboo WOX family.Bamboo WOX4 s and WOX5 s are conserved not only at the translational levels,but also at the genome level.AP2/ERF protein-binding elements and B3 protein-binding elements are found conservatively in the promoters of the bamboo WOX4 s.MYB proteinbinding elements and Dof protein-binding elements are found at the similar region of Bambusoideae WOX5s' promoters.Folwering-related MADS protein-binding sites is found in the promoters of bamboo WOX3 s.2.PheWOX11,PheWOX12 and PheWOX5 are specifically expressing in the roots of moso bamboo,and are sensitive to auxin treatment,which may involve in auxin-induced root formation.PheWOX4 c is active expression in stem apical tissues of moso bamboo,including shoot apical tissue and rhizome apical tissue,which may be involved in the maintenance,proliferation and differentiation of stem cells in apical meristem.PheWOX3 b is highly expressing in flower buds and pistils.Besides,the expression of PheWOX3 b increase in the early stage of bamboo flower development,which may involve in the flower morphogenesis during bamboo flowering.3.The proteins of PheWOX3b1.1,PheWOX3b1.2,PheWOX4 c,PheWOX13 a and PheWOX13 b are nuclear localization.PheWOX3b1.1,PheWOX3b1.2 and PheWOX4 c of WUS clade show no transcriptional activation activity,while PheWOX13 a and PheWOX13 b of ancient clade show transcriptional activation activity.Motif 6 of PheWOX13 a and PheWOX13 b is the transcriptional activation domain.PheWOX13 a can interact with GIF protein in yeast.4.PheWOX3b1.1 and PheWOX3b1.2 show different molecular function.Overexpression of PheWOX3b1.2 in rice shows the increasing number of vascular bundles in leaves,and abnormal position of vascular bundles in the leaf midvein,resulting in irregular and twisted leaves and an increase in leaf vein.However,the leaf phenotypes of overexpression of PheWOX3b1.1 in rice are similar with those in wild types.WUS box has an important influence on the function of PheWOX3 b in rice.