Phytoplasmas and Spiroplasmas: The Phytopathogenic Mollicutes of the Phloem

MacLean, Allyson M.; Hogenhout, Saskia A.

doi:10.1002/9781118382806.ch14

Cited by 5 publications

(3 citation statements)

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“…They are spherical to ovoid or irregular tubular in shape. Phytoplasmas are found in the phloem sieve tubes of plants and in the gut, salivary glands and other organs of sap-sucking insects (Hogenhout et al, 2008;MacLean & Hogenhout, 2012). Phytoplasmas overcome plant defences by producing specific proteins, called effectors (Bai et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Expression of phytoplasma‐induced witches’ broom disease symptoms in acid lime (Citrus aurantifolia) trees is affected by climatic conditions

et al. 2017

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Witches’ broom disease (WBD), caused by ‘Candidatus Phytoplasma aurantifolia’, is a serious disease of acid lime (Citrus aurantifolia) in Oman and the UAE. However, little is known about the distribution of phytoplasma and the expression of WBD symptoms in different geographical locations. A survey was carried out in 18 districts in Oman and the UAE covering 143 orchards and 5823 acid lime trees. ‘Candidatus Phytoplasma aurantifolia’ was detected in acid lime in all the 18 surveyed districts. However, the development of typical symptoms of WBD was only observed in 12 districts. Districts in which the phytoplasma was present but symptoms were not expressed were located either in desert areas or in areas characterized by semitropical conditions. Phylogenetic analysis of 16 phytoplasma isolates from trees developing WBD symptoms and six phytoplasma isolates from trees with no WBD symptoms showed that all isolates share an identical 16S rRNA sequence, belonging to subgroup II‐B. Quantitative PCR analysis showed that the concentration of phytoplasma is significantly higher (8800–801 000 copies) in leaves developing WBD symptoms compared to 2–268 copies in symptomless leaves from the same trees and 8–874 copies in acid lime trees from areas where disease symptoms were not expressed. The lack of expression of WBD symptoms under certain environmental conditions may suggest that symptom development and phytoplasma are affected by certain unfavourable environmental conditions. These findings could provide a basis for managing WBD through encouraging lime cultivation under climatic conditions less conducive to WBD symptom expression.

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Section: Introductionmentioning

confidence: 99%

Expression of phytoplasma‐induced witches’ broom disease symptoms in acid lime (Citrus aurantifolia) trees is affected by climatic conditions

et al. 2017

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“…Phytoplasma’, encode nine hypothetical proteins and five proteins with known functions. Two of the hypothetical proteins contain a sequence-variable mosaic (SVM) motif [ 16 ] and comprise SAP05 (AYWB_032), which is described as a putative effector protein [ 17 ] inducing the formation of smooth young rosette leaves that lack serrations along the leaf margin [ 18 ], and SAP30 (AYWB_402), which is similar to SAP11 containing an eukaryotic nuclear localisation signal [ 19 , 20 ]. This group of unique genes also includes two phytoplasma proteins involved in a suggested alternative pathway in the carbohydrate metabolism of phytoplasmas [ 7 , 13 , 21 ].…”

Section: Resultsmentioning

confidence: 99%

Complete genome determination and analysis of Acholeplasma oculi strain 19L, highlighting the loss of basic genetic features in the Acholeplasmataceae

et al. 2014

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BackgroundAcholeplasma oculi belongs to the Acholeplasmataceae family, comprising the genera Acholeplasma and ‘Candidatus Phytoplasma’. Acholeplasmas are ubiquitous saprophytic bacteria. Several isolates are derived from plants or animals, whereas phytoplasmas are characterised as intracellular parasitic pathogens of plant phloem and depend on insect vectors for their spread. The complete genome sequences for eight strains of this family have been resolved so far, all of which were determined depending on clone-based sequencing.ResultsThe A. oculi strain 19L chromosome was sequenced using two independent approaches. The first approach comprised sequencing by synthesis (Illumina) in combination with Sanger sequencing, while single molecule real time sequencing (PacBio) was used in the second. The genome was determined to be 1,587,120 bp in size. Sequencing by synthesis resulted in six large genome fragments, while the single molecule real time sequencing approach yielded one circular chromosome sequence. High-quality sequences were obtained by both strategies differing in six positions, which are interpreted as reliable variations present in the culture population. Our genome analysis revealed 1,471 protein-coding genes and highlighted the absence of the F1FO-type Na+ ATPase system and GroEL/ES chaperone. Comparison of the four available Acholeplasma sequences revealed a core-genome encoding 703 proteins and a pan-genome of 2,867 proteins.ConclusionsThe application of two state-of-the-art sequencing technologies highlights the potential of single molecule real time sequencing for complete genome determination. Comparative genome analyses revealed that the process of losing particular basic genetic features during genome reduction occurs in both genera, as indicated for several phytoplasma strains and at least A. oculi. The loss of the F1FO-type Na+ ATPase system may separate Acholeplasmataceae from other Mollicutes, while the loss of those genes encoding the chaperone GroEL/ES is not a rare exception in this bacterial class.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-931) contains supplementary material, which is available to authorized users.

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“…Because H. crudus is a con rmed vector of the palm disease termed lethal yellowing (LY) caused by the 16SrIV-A phytoplasma on the American continent [49,50], it is implicated as the putative vector of lethal bronzing (LB), a devastating palm disease caused by the ethal bronzing phytoplasma (16SrIV-D subgroup). Phytoplasmas are related to gram-positive bacteria and are obligate intracellular parasites of plants that are transmitted by phloem-feeding hemipteran insects, including leafhoppers, planthoppers and psyllids [25,26]. The LY phytoplasma results in yellowing, wilting and death of palms and has caused major outbreaks that resulted in the losses of millions of coconut palms (Cocos nucifera) throughout the Caribbean basin (need reference, the compendium of lethal yellowing should do, is a small book) as well as other and other palm species.…”

Section: Introductionmentioning

confidence: 99%

The Complete Mitochondrial Genome of The American Palm Cixiid, Haplaxius Crudus (Hemiptera: Cixiidae)

Komondy

Huguet‐Tapia

Ascunce

et al. 2020

Preprint

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Background Haplaxius crudus (the American palm cixiid) is a major insect pest of various economically important palms. H. crudus persists in tropical and subtropical regions where it is known to transmit the lethal yellowing (LY) phytoplasma. It has been implicated as the putative vector of Lethal bronzing (LB), a destructive phytoplasma-induced palm disease affecting over 16 species of ornamental and agricultural palms. To date, no mitochondrial genomes for species in the family Cixiidae are sequenced. Analysis of mitochondrial DNA sequences of H. crudus has proven useful for proper species diagnosis and population studies which could benefit management programs aimed at moving infective insects. These analyses describe the first mitochondrial genome from the American palm cixiid, Haplaxius crudus and an insect in the family Cixiidae. Results In this study, the complete mitochondrial genome of H. crudus was assembled and characterized from PacBio Sequel II long sequencing reads using the University of Florida’s HiPerGator supercomputer. The circular mitogenome of H. crudus is 15,845 bp long and encodes 37 mitochondrial genes (including 13 protein coding genes (PCGs), 22 tRNAs and 2 rRNAs) in addition to a putative non-coding internal control region. The nucleotide composition of H. crudus is asymmetric with a bias toward A and T (44.8 %A, 13.4 %C, 8.5 %G and 33.3 %T). Protein-coding genes (PCGs) possess the standard invertebrate mitochondrial start codons with few exceptions while the gene content and order of the H. crudus mitogenome is identical to most completely sequenced insect mitochondrial genomes. Phylogenetic analysis indicated that H. crudus is closely related to the planthopper in the family Delphacidae: N. lugens, which is the established sister group to Cixiidae. Conclusions Our studies have elucidated the first reference mitochondrial genome of Haplaxius crudus, providing structural analysis of the circular genome and encoded gene regions. The present results provide future opportunities to assess the diversity and origin of H. crudus. This study demonstrates the significance of understanding the structure and function of the mitochondrial genome to inform effective diagnostic and management strategies for insect pests.

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Phytoplasmas and Spiroplasmas: The Phytopathogenic Mollicutes of the Phloem

Cited by 5 publications

References 70 publications

Expression of phytoplasma‐induced witches’ broom disease symptoms in acid lime (Citrus aurantifolia) trees is affected by climatic conditions

Expression of phytoplasma‐induced witches’ broom disease symptoms in acid lime (Citrus aurantifolia) trees is affected by climatic conditions

Complete genome determination and analysis of Acholeplasma oculi strain 19L, highlighting the loss of basic genetic features in the Acholeplasmataceae

The Complete Mitochondrial Genome of The American Palm Cixiid, Haplaxius Crudus (Hemiptera: Cixiidae)

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