"Candidatus Phytoplasma oryzae", a novel phytoplasma taxon associated with rice yellow dwarf disease.
ABSTRACT In addition to rice yellow dwarf (RYD) phytoplasma, several phytoplasmas infect gramineous plants, including rice orange leaf, bermuda grass white leaf, brachiaria grass white leaf and sugarcane white leaf phytoplasmas. To investigate whether the RYD phytoplasma is a discrete, species-level taxon, several isolates of the aforementioned phytoplasmas were analysed using PCR-amplified 16S rDNA sequences. Two RYD isolates, RYD-J(T) and RYD-Th, were almost identical (99.2 %), but were distinct (similarities of 96.3-97.9 %) from other phytoplasma isolates of the RYD 16S-group. The notion that the RYD phytoplasma constitutes a unique taxon is also supported by its unique insect vector (Nephotettix sp.), its unique host plant in nature (rice) and its limited geographical distribution (Asia). In Southern blot analysis, chromosomal and extrachromosomal DNA probes of the RYD phytoplasma reportedly did not hybridize with those of closely related phytoplasmas. These properties of the RYD phytoplasma clearly indicate that it represents a novel taxon, 'Candidatus Phytoplasma oryzae'.
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ABSTRACT: 'Candidatus Phytoplasma mali' is a phytopathogenic bacterium of the family Acholeplasmataceae assigned to the class Mollicutes. This causative agent of the apple proliferation colonizes in Malus domestica the sieve tubes of the plant phloem resulting in a range of symptoms such as witches'- broom formation, reduced vigor and affecting size and quality of the crop. The disease is responsible for strong economical losses in Europe. Although the genome sequence of the pathogen is available, there is only limited information on expression of selected genes and metabolic key features that have not been examined on the transcriptomic or proteomic level so far. This situation is similar to many other phytoplasmas. In the work presented here, RNA-Seq and mass spectrometry shotgun techniques were applied on tissue samples from Nicotiana occidentalis infected by 'Ca. P. mali' strain AT providing insights into transcriptome and proteome of the pathogen. Data analysis highlights expression of 208 genes including 14 proteins located in the terminal inverted repeats of the linear chromosome. Beside a high portion of house keeping genes, the recently discussed chaperone GroES/GroEL is expressed. Furthermore, gene expression involved in formation of a type IVB and of the Sec-dependent secretion system was identified as well as the highly expressed putative pathogenicity-related SAP11-like effector protein. Metabolism of phytoplasmas depends on the uptake of spermidine/putescine, amino acids, co-factors, carbohydrates and in particular malate/citrate. The expression of these transporters was confirmed and the analysis of the carbohydrate cycle supports the suggested alternative energy-providing pathway for phytoplasmas releasing acetate and providing ATP. The phylogenetic analyses of malate dehydrogenase and acetate kinase in phytoplasmas show a closer relatedness to the Firmicutes in comparison to Mycoplasma species indicating an early divergence of the Acholeplasmataceae from the Mollicutes.PLoS ONE 01/2014; 9(4):e94391. · 3.53 Impact Factor
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ABSTRACT: In this study, the taxonomic position and group classification of the phytoplasma associated with a lethal yellowing-type disease (LYD) of coconut (Cocos nucifera L.) in Mozambique were addressed. Pairwise sequence similarity values based on alignment of near full-length 16SrRNA genes (1530 bp) revealed that the Mozambique coconut phytoplasma (LYDM) shared 100% identity with a comparable sequence derived from a phytoplasma strain (LDN), responsible for Awka wilt disease of coconut in Nigeria, and shared 99-99.6% identity with 16S rRNA sequences from strains associated with Cape St. Paul wilt (CSPW) disease of coconut in Ghana and Côte d'Ivoire. Similarity scores further determined the 16S rRNA gene of LYDM phytoplasma to share <97.5% sequence identity with all prior descriptions of 'Ca. Phytoplasma' species. Presence of unique regions in the 16S rRNA distinguished LYDM phytoplasma from all currently described 'Candidatus Phytoplasma' species, justifying its recognition as reference strain of a novel taxon, 'Candidatus Phytoplasma palmicola'. Virtual restriction fragment length polymorphism (RFLP) profiles of the F2n/R2 portion (1251 bp) of the 16S rRNA gene and pattern similarity coefficient values delineated coconut LYDM phytoplasma strains from Mozambique as new members of established group 16SrXXII, subgroup A (16SrXXII-A). Similarity coefficients of 0.97 were obtained for comparisons between subgroup 16SrXXII-A strains and CSPW phytoplasmas from Ghana and Côte d'Ivoire. On this basis, CSPW phytoplasma strains were designated as members of a new subgroup, 16SrXXII-B.INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY 02/2014; · 2.11 Impact Factor
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ABSTRACT: A phytoplasma was detected in golden beard grass (Chrysopogon acicalatus) displaying white leaf symptoms near vegetative fields at the Tatkone region in Myanmar, 2011. Based on restriction fragment length polymorphism analysis of PCR-amplified 16S rRNA genes, including the 16S-23S spacer region and part of the 23S rRNA gene, the phytoplasma was identified as a member of the Bermuda grass white leaf phytoplasma (BGWL) group. The golden beard grass white leaf phytoplasma (GBGWL) 16S rRNA gene sequence exhibited over 98.7% similarity with all members of BGWL group phytoplasmas and 99.5% similarity with Thailand Bermuda grass white leaf phytoplasma (AF248961). In addition, the GBGWL phytoplasma was confirmed to be a member of 'Candidatus Phytoplasma cynodontis' by phylogenetic analyses.Tropical Plant Pathology 02/2012; 37(1):76-79. · 0.51 Impact Factor