Molecular characterization, phylogenetic comparison and serological relationship of the Imp protein of several ‘<i>Candidatus</i> Phytoplasma aurantifolia’ strains

Siampour, Majid; Izadpanah, K.; Galetto, Luciana; Salehi, Mohammad; Marzachı̀, Cristina

doi:10.1111/j.1365-3059.2012.02662.x

Cited by 34 publications

(27 citation statements)

References 33 publications

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“…1.1) does not contain a C-terminal transmembrane region or cleavage sites, leading to the assumption that Imp is anchored to the phytoplasma cell membrane by an N-terminal transmembrane region (Berg et al, 1999;Morton et al, 2003). These findings were later supported by analysis of Imp-encoding genes from a number of other phytoplasmas (Kakizawa et al, 2009;Siampour et al, 2013).…”

Section: Predicted Protein Structuresupporting

confidence: 50%

Immunodominant membrane proteins of phytoplasmas

2016

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Phytoplasmas are plant-pathogenic, phloem-colonizing, cell wall-less microorganisms that are primarily dependent on insect transmission for their spread and survival. The life cycle of phytoplasmas involves replication in insects and host plants. Until recently, phytoplasmas have resisted all attempts at cultivation in cell-free media, making these pathogens poorly characterized on a physiological and biochemical basis. However, host-pathogen relationships can be studied by investigating immunodominant membrane proteins (IDPs), which are located on the exterior surfaces of phytoplasma cells and are the most abundant proteins of the cell membrane. These membrane proteins come in direct contact with both insect and plant hosts and are thought to play a crucial role in phytoplasma spread both within the plant and by insect vectors. Therefore, there is great interest in studying this class of proteins. We summarize and discuss important investigations about these membrane proteins, which have already provided a better understanding of the host-phytoplasma relationship.

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Section: Predicted Protein Structuresupporting

confidence: 50%

Immunodominant membrane proteins of phytoplasmas

2016

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“…Nothing is known of the role of "Ca. Phytoplasma asteris" imp in the plant, although this gene is under positive selection in different phytoplasmas (13,15). Imp of "Ca.…”

Section: Discussionmentioning

confidence: 99%

“…In vitro studies have also shown that phytoplasma immunodominant membrane proteins interact with vector proteins (10,11) and plant proteins (12) and are subjected to strong positive selection (13)(14)(15). Moreover, phytoplasmas can modulate their genome expression according to the infection stage and the infected host species, as suggested by microarray analysis (16) and gene expression study of pathogen transcription factors (17) and of genes lying within potential mobile units (18).…”

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confidence: 99%

Decreasing Global Transcript Levels over Time Suggest that Phytoplasma Cells Enter Stationary Phase during Plant and Insect Colonization

Pacifico

Galetto

Rashidi

et al. 2015

Appl Environ Microbiol

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To highlight different transcriptional behaviors of the phytoplasma in the plant and animal host, expression of 14 genes of "Candidatus Phytoplasma asteris," chrysanthemum yellows strain, was investigated at different times following the infection of a plant host (Arabidopsis thaliana) and two insect vector species (Macrosteles quadripunctulatus and Euscelidius variegatus). Target genes were selected among those encoding antigenic membrane proteins, membrane transporters, secreted proteins, and general enzymes. Transcripts were detected for all analyzed genes in the three hosts; in particular, those encoding the antigenic membrane protein Amp, elements of the mechanosensitive channel, and two of the four secreted proteins (SAP54 and TENGU) were highly accumulated, suggesting that they play important roles in phytoplasma physiology during the infection cycle. Most transcripts were present at higher abundance in the plant host than in the insect hosts. Generally, transcript levels of the selected genes decreased significantly during infection of A. thaliana and M. quadripunctulatus but were more constant in E. variegatus. Such decreases may be explained by the fact that only a fraction of the phytoplasma population was transcribing, while the remaining part was aging to a stationary phase. This strategy might improve long-term survival, thereby increasing the likelihood that the pathogen may be acquired by a vector and/or inoculated to a healthy plant. Phytoplasmas are wall-less plant-pathogenic bacteria, classified as "Candidatus Phytoplasma" spp. (1). They belong to the class Mollicutes and infect a wide variety of plants, causing heavy crop losses in many different countries (2). Phytoplasmas are phloem limited in the infected plant, and they cause severe symptoms (yellowing, dwarfism, and phyllody), often leading to plant death. They are transmitted by phloem-feeding Hemipteran vectors (leafhoppers, planthoppers, and psyllids) in a persistent propagative manner (3).Phytoplasmas are obligate parasites that depend on host cells for the uptake of essential compounds such as sugars, amino acids, ions, and nucleotide precursors (4). Consistent with this lifestyle, phytoplasmas have very small, A/T-rich genomes, ranging from 530 to 1,350 kb in size (5), that lack essential metabolic pathways, such as ATP synthesis. This genome condensation reflects the phytoplasma adaptation to nutrient-rich environments such as the plant phloem (6) and helps explain why these pathogens are not cultivable under axenic conditions (7).Although the pathogenicity mechanisms are still largely unclear, phytoplasmas influence plant metabolism both directly, through a set of membrane proteins acting as molecular carriers (6), and indirectly, through secretion of effector proteins (8,9). In vitro studies have also shown that phytoplasma immunodominant membrane proteins interact with vector proteins (10, 11) and plant proteins (12) and are subjected to strong positive selection (13-15). Moreover, phytoplasmas can modulate their genome express...

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“…An isolate of LWB phytoplasma maintained in periwinkle (Siampour et al, 2013) was used in this study. Total DNA from LWB-infected and healthy periwinkles was extracted using the cetyltrimethylammonium bromide method (Maixner et al, 1995).…”

Section: Methodsmentioning

confidence: 99%

“…P. aurantifolia' (16SrII), the causal agent of LWB disease, is restricted to a few genes that do not include SVMs or PMUs. Based on the analysis of conserved genes, including 16S rRNA and the immunodominant membrane protein, LWB phytoplasma was shown to be closely related to 16SrII phytoplasmas (Siampour et al, 2013). In the present study, we obtained sequence information from different regions of the genome of this phytoplasma (including SVM regions) and compared them with their counterparts in PnWB or phytoplasmas of other 16Sr groups for which the genome sequence data are available.…”

Section: Introductionmentioning

confidence: 99%

Identification and characterization of conserved and variable regions of lime witches’ broom phytoplasma genome

et al. 2015

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Several segments (,20 kbp) of the lime witches' broom (LWB) phytoplasma genome (16SrII group) were sequenced and analysed. A 5.7 kbp segment (LWB-C) included conserved genes whose phylogenetic tree was consistent with that generated using 16S rRNA genes. Another 6.4 kbp LWB phytoplasma genome segment (LWB-NC) was structurally similar to the putative mobile unit or sequence variable mosaic genomic region of phytoplasmas, although it represented a new arrangement of genes or pseudogenes such as phage-related protein genes and tra5 insertion sequences. Sequence-and phylogenetic-based evidence suggested that LWB-NC is a genomic region which includes horizontally transferred genes and could be regarded as a hot region to incorporate more foreign genes into the genome of LWB phytoplasma. The presence of phylogenetically related fragments of retroelements was also verified in the LWB phytoplasma genome. Putative intragenomic retrotransposition or retrohoming of these elements might have been determinant in shaping and manipulating the LWB phytoplasma genome. Altogether, the results of this study suggested that the genome of LWB phytoplasma is colonized by a variety of genes that have been acquired through horizontal gene transfer events, which may have further affected the genome through intragenomic mobility and insertion at cognate or incognate sites. Some of these genes are expected to have been involved in the development of features specific to LWB phytoplasma.

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Molecular characterization, phylogenetic comparison and serological relationship of the Imp protein of several ‘Candidatus Phytoplasma aurantifolia’ strains

Cited by 34 publications

References 33 publications

Immunodominant membrane proteins of phytoplasmas

Immunodominant membrane proteins of phytoplasmas

Decreasing Global Transcript Levels over Time Suggest that Phytoplasma Cells Enter Stationary Phase during Plant and Insect Colonization

Identification and characterization of conserved and variable regions of lime witches’ broom phytoplasma genome

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