Viroid Diseases in Pome and Stone Fruit Trees and Koch’s Postulates: A Critical Assessment

Serio, Francesco Di; Ambrós, Silvia; Shimmen, Teruo; Flores, Ricardo; Navarro, Beatriz

doi:10.3390/v10110612

Cited by 23 publications

(16 citation statements)

References 91 publications

(133 reference statements)

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“…Although the FHVd-LR structural features are closer to the VL-satRNA of LTSV and to cscRNAs than to viroids, we are unable to predict the biological nature of this novel Vd-LRNA from fig. Only bioassays may answer the specific question of whether FHVd-LR is able to replicate autonomously and systemically infect fig (Di Serio et al, 2018a). In this respect, experiments to test the transmission of FHVd-LR to virus-free fig plants by grafting and slash-inoculation of RNA preparations enriched in Vd-LRNAs and of in vitro-generated dimeric head-to tail transcripts are ongoing.…”

Section: Discussionmentioning

confidence: 99%

“…In this respect, experiments to test the transmission of FHVd-LR to virus-free fig plants by grafting and slash-inoculation of RNA preparations enriched in Vd-LRNAs and of in vitro -generated dimeric head-to tail transcripts are ongoing. Slash-inoculated plants were negative by RT-PCR and northern blot assays one and two months post-inoculation, but such bioassays in woody hosts may require longer times for systemic infection ( Di Serio et al, 2018a ).…”

Section: Discussionmentioning

confidence: 99%

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Novel Fig-Associated Viroid-Like RNAs Containing Hammerhead Ribozymes in Both Polarity Strands Identified by High-Throughput Sequencing

Olmedo-Velarde

Navarro

et al. 2020

Front. Microbiol.

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Based on high-throughput sequencing (HTS) data, the existence of viroid-like RNAs (Vd-LRNAs) associated with fig trees grown in the Hawaiian Islands has been predicted. One of these RNAs has been characterized as a circular RNA ranging in size from 357 to 360 nucleotides. Structural and biochemical features of this RNA, tentatively named fig hammerhead viroid-like RNA (FHVd-LR), markedly resemble those previously reported for several viroids and viroid-like satellite RNAs (Vd-LsatRNAs), which are non-proteincoding RNAs infecting their hosts autonomously and in combination with a helper virus, respectively. The full-length sequence of FHVd-LR variants was determined by RT-PCR, cloning, and sequencing. Despite a low global sequence identity with known viroids and Vd-LsatRNAs, FHVd-LR contains a hammerhead ribozyme (HRz) in each polarity strand. Northern blot hybridization assays identified the circular and linear forms of both polarity strands of FHVd-LR and showed that one strand, assigned the (+) polarity, accumulates at higher levels than the (−) polarity strand in vivo. The (+) polarity RNA assumes a rodlike secondary structure of minimal free energy with the conserved domains of the HRzs located in opposition to each other, a feature typical of several viroids and Vd-LRNAs. The HRzs of both FHVd-LR polarity strands were shown to be active in vitro during transcription, self-cleaving the RNAs at the predicted sites. These data, together with the sequence variability observed in the cloned and sequenced full-length variants, indicate that FHVd-LR is a novel viroid or Vd-LsatRNA. According to HTS data, the coexistence of FHVd-LR of different sizes in the same host cannot be excluded. The relationships of FHVd-LR with previously reported viroids and Vd-LsatRNAs, and the need to perform bioassays to conclusively clarify the biological nature of this circular RNA, are discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Novel Fig-Associated Viroid-Like RNAs Containing Hammerhead Ribozymes in Both Polarity Strands Identified by High-Throughput Sequencing

Olmedo-Velarde

Navarro

et al. 2020

Front. Microbiol.

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“…PLMVd is the only viroid shared by all five nectarine trees that displayed three leaf disease phenotypes (asymptomatic, bleached, and chlorotic mottle) in this study. Some studies have shown that PLMVd infection can be associated with albinism (peach calico, PC) and green mosaic symptoms, and revealed a close association between the albino phenotype and variants containing an insertion of 12–14 nt, folding into a hairpin capped by a U-rich loop in the proposed PLMVd branched secondary structure 21,35 . It is worth noting that we did not find this 12–14 nt insertion in this study.…”

Section: Discussionmentioning

confidence: 99%

Analyses of virus/viroid communities in nectarine trees by next-generation sequencing and insight into viral synergisms implication in host disease symptoms

Na³

et al. 2019

Sci Rep

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We analyzed virus and viroid communities in five individual trees of two nectarine cultivars with different disease phenotypes using next-generation sequencing technology. Different viral communities were found in different cultivars and individual trees. A total of eight viruses and one viroid in five families were identified in a single tree. To our knowledge, this is the first report showing that the most-frequently identified viral and viroid species co-infect a single individual peach tree, and is also the first report of peach virus D infecting Prunus in China. Combining analyses of genetic variation and sRNA data for co-infecting viruses/viroid in individual trees revealed for the first time that viral synergisms involving a few virus genera in the Betaflexiviridae , Closteroviridae , and Luteoviridae families play a role in determining disease symptoms. Evolutionary analysis of one of the most dominant peach pathogens, peach latent mosaic viroid (PLMVd), shows that the PLMVd sequences recovered from symptomatic and asymptomatic nectarine leaves did not all cluster together, and intra-isolate divergent sequence variants co-infected individual trees. Our study provides insight into the role that mixed viral/viroid communities infecting nectarine play in host symptom development, and will be important in further studies of epidemiological features of host-pathogen interactions.

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Section: Iscovery Hos Ts and Symp Tomatologymentioning

confidence: 99%

“…(Hataya et al, 2017; Vamenani et al, 2019). HSVd infection in most of these hosts is symptomless but other diseases have been identified in fruit trees associated with diverse isolates of this viroid (Di Serio et al, 2018). In particular, cachexia in citrus (Semancik et al, 1988) and fruit diseases in trees of the genus Prunus : plum and peach (Sano et al, 1989) (Figure 1c), apricot (Amari et al, 2007) (Figure 1d), and sweet cherry (Xu et al, 2017).…”

Section: Discovery Hosts and Symptomatologymentioning

confidence: 99%

Hop stunt viroid: A polyphagous pathogenic RNA that has shed light on viroid–host interactions

Marquez‐Molins

Gómez

Pallás

2020

Molecular Plant Pathology

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Taxonomy Hop stunt viroid (HSVd) is the type species of the genus Hostuviroid (family Pospiviroidae). The other species of this genus is Dahlia latent viroid, which presents an identical central conserved region (CCR) but lacks other structural hallmarks present in Hop stunt viroid. HSVd replication occurs in the nucleus through an asymmetric rolling‐circle model as in the other members of the family Pospiviroidae, which also includes the genera Pospiviroid, Cocadviroid, Apscaviroid, and Coleoviroid. Physical properties Hop stunt viroid consists of a single‐stranded, circular RNA of 295–303 nucleotides depending on isolates and sequence variants. The most stable secondary structure is a rod‐like or quasi‐rod‐like conformation with two characteristic domains: a CCR and a terminal conserved hairpin similar to that of cocadviroids. HSVd lacks a terminal conserved region. Hosts and symptoms HSVd infects a very broad range of natural hosts and has been reported to be the causal agent of five different diseases (citrus cachexia, cucumber pale fruit, peach and plum apple apricot distortion, and hop stunt). It is distributed worldwide. Transmission HSVd is transmitted mechanically and by seed.

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Viroid Diseases in Pome and Stone Fruit Trees and Koch’s Postulates: A Critical Assessment

Cited by 23 publications

References 91 publications

Novel Fig-Associated Viroid-Like RNAs Containing Hammerhead Ribozymes in Both Polarity Strands Identified by High-Throughput Sequencing

Novel Fig-Associated Viroid-Like RNAs Containing Hammerhead Ribozymes in Both Polarity Strands Identified by High-Throughput Sequencing

Analyses of virus/viroid communities in nectarine trees by next-generation sequencing and insight into viral synergisms implication in host disease symptoms

Hop stunt viroid: A polyphagous pathogenic RNA that has shed light on viroid–host interactions

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