The genome biology of phytoplasma: modulators of plants and insects

Sugio, Akiko; Hogenhout, Saskia A.

doi:10.1016/j.mib.2012.04.002

Cited by 84 publications

(78 citation statements)

References 52 publications

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“…About 50 putative secreted proteins are present in phytoplasma genomes, and these effector genes differ from those found in other plant-pathogenic bacteria (71). Some of these have been shown to encode functional effectors, including SAP11, SAP54, SAP67, SAP68, and TENGU (8). SAP11, known to induce a bushy morphology and to enhance vector fitness by blocking jasmonic acid biosynthesis in plants (72), was not found in the draft genome of CYP, and it was not detected by PCR with specific primers designed for the closely related AY-WB phytoplasma (73).…”

Section: Discussionmentioning

confidence: 99%

“…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).…”

mentioning

confidence: 99%

“…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)(14)(15).…”

mentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

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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show abstract

“…Because the signaling pathways of the immune receptors detecting flagellin, EF-Tu, and chitin overlap, it is possible that fungal effectors can target the pathways activated by bacterial flagellin and EF-Tu and vice versa. Diverse phytoplasma species elicit developmental malformations in their host plants (Sugio and Hogenhout 2012). They secrete effectors that modulate plant development and plant-insect interactions, therefore ensuring the successful transmission of these obligate and insect-vectored bacterial pathogens.…”

Section: Effector-targeted Pathways: Functional Redundancy Among Pathmentioning

confidence: 99%

Effector Biology of Plant-Associated Organisms: Concepts and Perspectives

Win

Chaparro-Garcia

Belhaj

et al. 2012

Cold Spring Harbor Symposia on Quantitative Biology

357

329

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Every plant is closely associated with a variety of living organisms. Therefore, deciphering how plants interact with mutualistic and parasitic organisms is essential for a comprehensive understanding of the biology of plants. The field of plant-biotic interactions has recently coalesced around an integrated model. Major classes of molecular players both from plants and their associated organisms have been revealed. These include cell surface and intracellular immune receptors of plants as well as apoplastic and host-cell-translocated (cytoplasmic) effectors of the invading organism. This article focuses on effectors, molecules secreted by plant-associated organisms that alter plant processes. Effectors have emerged as a central class of molecules in our integrated view of plant-microbe interactions. Their study has significantly contributed to advancing our knowledge of plant hormones, plant development, plant receptors, and epigenetics. Many pathogen effectors are extraordinary examples of biological innovation; they include some of the most remarkable proteins known to function inside plant cells. Here, we review some of the key concepts that have emerged from the study of the effectors of plant-associated organisms. In particular, we focus on how effectors function in plant tissues and discuss future perspectives in the field of effector biology.

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“…Thus, the virulent strain may suppress the plant immune system more effectively than the avirulent strain. The variation in symptoms observed in infected plants coincides with differential presence of phytoplasma effector genes (Sugio and Hogenhout, 2012). Whether effector proteins are involved in changing the odor profile is unknown.…”

Section: Discussionmentioning

confidence: 99%

Apple Proliferation Phytoplasma Influences the Pattern of Plant Volatiles Emitted Depending on Pathogen Virulence

et al. 2016

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Apple proliferation (AP) and pear decline (PD) are the most severe diseases in pome fruit growing areas. AP-infected trees show typical symptoms such as witches' broom, enlarged stipules, tasteless, and dwarf fruits. PD-infected pears show a progressive weakening, reduced terminal growth, smaller fruits, and die within weeks (quick decline) or years (slow decline). The diseases are caused by the cell-wall lacking bacteria Candidatus Phytoplasma mali (AP phytoplasma) and Ca. P. pyri (PD phytoplasma), respectively. In previous studies it has been shown that AP-infected apple trees emitted higher amounts of the sesquiterpene β-caryophyllene, an attractant of the insect vector Cacopsylla picta (Hemiptera: Psyllidae), thereby facilitating the dispersal of AP phytoplasma. In the present study, volatile organic compounds (VOCs) occurring in the headspace of plants infected with Ca. P. mali strains causing different severity of symptoms in apple plants were collected, analyzed, and identified. Headspace samples from healthy and AP-infected model plant tobacco (Nicotiana occidentalis) and apple (Malus domestica) as well as from healthy and PD-infected pear (Pyrus communis) were investigated via thermodesorption and GC-MS analysis. Significantly higher concentrations of ethyl benzoate were produced in all phytoplasma-infected plants compared to healthy ones and an as yet unidentified sesquiterpene differed between the odor bouquets of healthy and by Ca. P. mali infected tobacco plants. Additionally, statistically significant higher amounts of both compounds were measured in the headspace of plants infected by the virulent AP strain. In apple, significantly higher concentrations of ethyl benzoate and methyl salicylate were observed for trees infected with strains of Ca. P. mali. Ethyl benzoate was also detected in the headspace of pear trees infected with Ca. P. pyri.

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The genome biology of phytoplasma: modulators of plants and insects

Cited by 84 publications

References 52 publications

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

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

Effector Biology of Plant-Associated Organisms: Concepts and Perspectives

Apple Proliferation Phytoplasma Influences the Pattern of Plant Volatiles Emitted Depending on Pathogen Virulence

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