Identification Of Pathogen Of Leaf Spot Disease Of Dracaena Sanderiana And Cloning Of Pathogenesis Related Protein Gene

Dracaena sanderiana is one of the most important export ornamental plants in China.A serious leaf spot disease was found on the D.sanderiana.Identification of the pathogen of this disease is of great significance to the prevention and control of the disease.Peroxidase(peroxidase)is a kind of oxidoreductase widely existing in organisms.There are many types of peroxidase that have many important functions in plants and are involved in many important functions in plants,including resistance to plant diseases.In this study,the pathogen identification,whole genome sequencing analysis and cloning of the full-length peroxidase gene of D.sanderiana were carried out with D.sanderiana as the research object.The main findings of this study are as follows :(1)Three strains of bacteria FGZ-ZJ,FGZ-NL and FGZ-HK were isolated from the leaf spot disease of D.sanderiana in Guangdong,Guangxi and Hainan.By osmotic inoculation,the three strains of bacteria were proved to be the pathogen of leaf spot of the D.sanderiana.It was identified as gram-negative rod-shaped bacteria.It was identified as Pantoea stewartia by 16 S r DNA.The genes of gal E,pst C+pst S and glm S were further amplified.The above four genes were splice together with the whole gene sequences of the subspecies identified by NCBI(national center of Bioinformation)to construct a polygenic phylogenetic evolutionary tree.The results showed that the three strains of bacteria were identified as p.stewartii subsp.indologenes?(2)Whole genome sequencing of FGZ-ZJ strain was performed.Three sequences were eventually assembled,one for the bacterial genome and two for the plasmid.Genome size was 4,982,863 bp,GC content was 53.54%,and a total of 4654 encoded genes,12 pseudogenes,8 regularly spaced short palindromic repeats(CRISPR)and 2 prophages were predicted.This strain was identified as p.stewartii subsp.indologenes based on the average nucleotide identity(ANI).(3)A about 1500 bp fragments were amplified from D.sanderiana genomic DNA were amplified using degenerate primers.The fragments were cloned and sequenced to be partial POD gene which were named FGZ-POD-X1 and FGZ-POD-X2.The flanking sequences were amplified using hi TAIL-PCR and the flanking sequences were assembled successfully to the sequences of FGZ-POD-X1 and FGZ-POD-X2.The assembled sequence was 3419 bp.The gene was predicted using Softberry software using maize as the reference gene,the gene contain 4 exons,transcriptional start site and poly A tail.Blast search proved that the gene was POD.The full-length POD gene of D.sanderiana was successfully cloned and the gene was named FGZ-POD-X2FL...