SpCLE Polypeptide Regulates Arabidopsis Vascular Tissue Development And Analysis Of Poplar CLE Gene Family

Accumulated evidence has revealed that small peptide family termed CLE(CLAVATA3/Endosperm Surrounding Region-related)peptide family is suggested to function as an intercellular signaling molecule involved in regulating various plant developmental processes.However,little is known about CLE peptides in regulating phloem development.Furthermore,function of CLE peptides in tree development is unclear.This research will provide a theoretical knowledge and gentic materials for CLE peptide in regulating phloem development and tree plant development as well,especially in regulation of woody plant vascular development.In this study,we first investigated the function a new CLE peptide named SpCLE peptide in regulating phloem development.And we tried to search its potential receptor and down components,and to establish a model for SpCLE peptide in regulating phloem development.This will provide a theoretical knowledge for regulation of phloem development.Secondly,we performed a sysmatic and detailed analysis of CLE gene family in Populus trichocarpa from CLE gene characteristic to its potential functions,which provides a fundamental insight into the role of CLE peptide in poplar development and in response to biotic and abiotic stress.The main conclusions were as follows:(1)SpCLE peptide specifically repressed Arabidopsis root phloem differentiation,but it had no effects on cambium and xylem development,indicating that SpCLE peptide is a new signaling molecular involved in regulation of phloem development.CLV2 as a potential receptor of SpCLE peptide can mediate SpCLE peptide signaling to suppress Arabidopsis root growth and phloem differentiation,furthermore,WOX4,WOX14 and HD-ZIP family were not down components of SpCLE peptide in repression of phloem differentiation,implying that unknown molecular is involved in SpCLE-CLV2 signaling pathway to regulate phloem development.However,function of WOX4,WOX14 and HD-ZIP family need further study.(2)50 CLE genes were identified from Populus genome by carrying out bioinformatic approaches.In line with Arabidopsis CLE gene family,Populus trichocarpa CLE genes also had a conserved CLE motif at C-terminal and a signal peptide at N-terminal.Based on sequence similarity 50CLE genes were grouped into 4 major subgroups and each subgroup shared a similar CLE motif,but some arnica acid is different which may be related with their diver roles.Gene structure analysis showed that 13 CLE genes contain intron.50CLE genes distributed differently on chromosomes,and some poplar CLE peptide share a similar or identical CLE motif scattered over on different chromosome implying a duplication events during evolution.A maximum likelihood method was performed to establish phylogenic tree between Arabidopsis and Populus CLE protein based on 13 amino acid CLE motifs.Results showed that some poplar CLE peptide share an identical CLE motif with Arabidopsis CLE41/44,CLE9/CLE10 and CLE45 peptide,pointing out a same or similar function of these poplar CLE peptide in tree development.Based on microarray data,poplar CLE genes played an important role in shoot apical meristem and vascular development.In addition,poplar CLE genes also played an essential role in response to biotic and abiotic stress,including hypoxia,wounding,aluminium stress,water defect,pathogen infection et al.