Project description:BackgroundJWB phytoplasma is a kind of insect-transmitted and uncultivable bacterial plant pathogen causeing a destructive Jujube disease. To date, no genome information about JWB phytoplasma has been published, which hindered its characterization at genomic level. To understand its pathogenicity and ecology, the genome of a JWB phytoplasma isolate jwb-nky was sequenced and compared with other phytoplasmas enabled us to explore the mechanisms of genomic rearrangement.ResultsThe complete genome sequence of JWB phytoplasma (jwb-nky) was determined, which consisting of one circular chromosome of 750,803 bp with a GC content of 23.3%. 694 protein-encoding genes, 2 operons for rRNA genes and 31 tRNA genes as well as 4 potential mobile units (PMUs) containing clusters of DNA repeats were identified. Based on PHIbaes analysis, a large number of genes were genome-specific and approximately 13% of JWB phytoplasma genes were predicted to be associated with virulence. Although transporters for maltose, dipeptides/oligopeptides, spermidine/putrescine, cobalt, Mn/Zn and methionine were identified, KEGG pathway analysis revealed the reduced metabolic capabilities of JWB phytoplasma. Comparative genome analyses between JWB phytoplasma and other phytoplasmas shows the occurrence of large-scale gene rearrangements. The low synteny with other phytoplasmas indicated that the expansion of multiple gene families/duplication probably occurred separately after differentiation.ConclusionsIn this study, the complete genome sequence of a JWB phytoplasma isolate jwb-nky that causing JWB disease was reported for the first time and a number of species-specific genes were identified in the genome. The study enhanced our understandings about genomic basis and the pathogenicity mechanism of this pathogen, which will aid in the development of improved strategies for efficient management of JWB diseases.
Project description:Phytoplasmas are plant pathogenic bacteria that have no cell wall and are responsible for major crop losses throughout the world. Phytoplasma-infected plants show a variety of symptoms and the mechanisms they use to physiologically alter the host plants are of considerable interest, but poorly understood. In this study we undertook a detailed analysis of Paulownia infected by Paulownia witches'-broom (PaWB) Phytoplasma using high-throughput mRNA sequencing (RNA-Seq) and digital gene expression (DGE). RNA-Seq analysis identified 74,831 unigenes, which were subsequently used as reference sequences for DGE analysis of diseased and healthy Paulownia in field grown and tissue cultured plants. Our study revealed that dramatic changes occurred in the gene expression profile of Paulownia after PaWB Phytoplasma infection. Genes encoding key enzymes in cytokinin biosynthesis, such as isopentenyl diphosphate isomerase and isopentenyltransferase, were significantly induced in the infected Paulownia. Genes involved in cell wall biosynthesis and degradation were largely up-regulated and genes related to photosynthesis were down-regulated after PaWB Phytoplasma infection. Our systematic analysis provides comprehensive transcriptomic data about plants infected by Phytoplasma. This information will help further our understanding of the detailed interaction mechanisms between plants and Phytoplasma.
Project description:In the 2019-2020 growing season, two corn fields located in İmamoğlu town (Adana Province, Turkey) were surveyed following the appearance of phytoplasma-like symptoms on maize plants. A total of 40 samples were collected and tested in first-round and nested PCR using universal primer pairs P1/P7 and R16F2n/R16R2, respectively. All maize-diseased plants reacted positively, whilst no PCR amplifications were obtained from asymptomatic plants. Blast sequence analysis of R16F2n/R16R2-primed amplicons from different maize isolates showed 99.2% to 100% of identity with the 16S rRNA gene of Ligustrum witches' broom phytoplasma (LiWBP). To gain additional molecular information on the 16S ribosomal RNA and 23S rRNA intergenic spacer region of LiWBP, not identified previously, the P1/P7-primed amplicons were also sequenced and analyzed. The results show that maize isolates from Turkey share 99.6% to 100% of identity among them, whereas the highest identity found (91%) was with members of groups 16SrII and 16SrXXV (peanut and tea witches' broom groups, respectively). This distant relationship between LiWBP and members of 16SrII and XXV was also confirmed by RFLP and phylogenetic analyses. This is the first finding of LiWBP on maize in nature, where it was found responsible for phyllody disease of corn plants in Turkey. The additional molecular information acquired in this study on the 16S-23S rRNA intergenic spacer region of LiWBP further corroborates its distant relationship to any other phytoplasma groups.