The pectic polysaccharide rhamnogalacturonan Ⅱ (RG-Ⅱ) is present in all plant species.Even though the structures of the RG-Ⅱ are very complex,the sugar composition of the RG-Ⅱ is extremely evolutionary conserved and contain at least 12different glycosyl residues.Among its component sugar is the seldom-conserved eight-carbon monosaccharides 3-deoxy-D-manno-octulosonic acid (Kdo) which is required for pollen tube growth and elongation.Furthermore,the phosphorylated bioprecursor of the KDO is synthesized by 3-Deoxy-D-manno-octulosonate 8-phosphate (KDO8P) synthase (AtkdsA1 and AtkdsA2 can code the synthase in Arabidopsis thaliana),and the biosynthetic pathway is also conserved between plants and Gram-negative bacteria.It can be seen that KDO-8P synthase plays a key role in structure stability.A full-length cDNA of encoding KDO-8P synthase gene was isolated from Phyllostachys heterocycla through RT-PCR,and named as PeAtkdsA (GenBank accession number: FP100420).The length of PeAtkdsA is 1207 bp,which contain an open reading frame encoding 291 amino acids.The result of amino acid sequence alignment analysis showed that PeKDO-8P synthase had high identities with other KDO-8P synthase in Oryza sativa,Zea mays,Brachypodium distachyon,Ricinus communis,Aquifex Aeolicus,Vibrio Cholerae,Physcomitrella,Haemophilus influenzae,Arabidopsis thaliana,E.Coli, Burkholderia Ambifaria, Selaginella moellendorffii, Coccomyxa subellipsoidea,especially with KDO-8P synthase from Oryza sativa up to 95%.Phylogenetic tree analysis showed that there were remarkably different branch sites.Tissue specific expression showed that PeKDSA expressed in root,stem,and leaf,much higher in root,which was similar with AtkdsA2 from Arabidopsis thaliana.In order to find out the difference and mechanism with different species,the structure of PeKDO-8P synthase should be analyzed.So in the research,PeKDSA was constructed into the expression vector pESAY-E1 and the fusion protein in expression was induced in E.coli strains:BL21(DE3) and RosettaTM(DE3).Then fusion protein was purified through steps chromatography (affinity chromatography and SEC).Native PAGE and SEC analysis shows that PeKDOPS protein mainly exists as tetramer,and SDS-PAGE shows the fusion protein has high degree of purity.Finally microcrystal was selected from the purity protein.These works provide the first step for its structure determination,or other,its function illumination from molecular lever.