scholarly journals Analysis of Sequence Polymorphism and Population Structure of Tomato chlorotic dwarf viroid and Potato spindle tuber viroid in Viroid-Infected Tomato Plants

Viruses ◽  
2012 ◽  
Vol 4 (6) ◽  
pp. 940-953 ◽  
Author(s):  
Xianzhou Nie
2001 ◽  
Vol 14 (11) ◽  
pp. 1332-1334 ◽  
Author(s):  
Asuka Itaya ◽  
Alexey Folimonov ◽  
Yoshie Matsuda ◽  
Richard S. Nelson ◽  
Biao Ding

Potato spindle tuber viroid (PSTVd), an RNA plant pathogen encoding no known proteins, induces systemic symptoms on tomato plants. We report detection of small RNAs of approximately 25 nucleotides with sequence specificity to PSTVd in infected plants: an indication of the presence of RNA silencing. RNA silencing, however, did not appear to be responsible for the differing symptoms induced by a mild and a severe strain of PSTVd. The unique structural and biological features of viroids make them attractive experimental tools to investigate mechanisms of RNA silencing and pathogen counterdefense.


Plant Disease ◽  
2015 ◽  
Vol 99 (6) ◽  
pp. 770-775 ◽  
Author(s):  
A. E. Mackie ◽  
B. A. Coutts ◽  
M. J. Barbetti ◽  
B. C. Rodoni ◽  
S. J. McKirdy ◽  
...  

The length of time Potato spindle tuber viroid (PSTVd) remained infective in extracted tomato leaf sap on common surfaces and the effectiveness of disinfectants against it were investigated. When sap from PSTVd-infected tomato leaves was applied to eight common surfaces (cotton, wood, rubber tire, leather, metal, plastic, human skin, and string) and left for various periods of time (5 min to 24 h) before rehydrating the surface and rubbing onto healthy tomato plants, PSTVd remained infective for 24 h on all surfaces except human skin. It survived best on leather, plastic, and string. It survived less well after 6 h on wood, cotton, and rubber and after 60 min on metal. On human skin, PSTVd remained infective for only 30 min. In general, rubbing surfaces contaminated with dried infective sap directly onto leaves caused less infection than when the sap was rehydrated with distilled water but overall results were similar. The effectiveness of five disinfectant agents at inactivating PSTVd in sap extracts was investigated by adding them to sap from PSTVd-infected leaves before rubbing the treated sap onto leaves of healthy tomato plants. Of the disinfectants tested, 20% nonfat dried skim milk and a 1:4 dilution of household bleach (active ingredient sodium hypochlorite) were the most effective at inactivating PSTVd infectivity in infective sap. When reverse-transcription polymerase chain reaction was used to test the activity of the five disinfectants against PSTVd in infective sap, it detected PSTVd in all instances except in sap treated with 20% nonfat dried skim milk. This study highlights the stability of PSTVd in infective sap and the critical importance of utilizing hygiene practices such as decontamination of clothing, tools, and machinery, along with other control measures, to ensure effective management of PSTVd and, wherever possible, its elimination in solanaceous crops.


2010 ◽  
Vol 391 (12) ◽  
Author(s):  
Natalie Diermann ◽  
Jaroslav Matoušek ◽  
Markus Junge ◽  
Detlev Riesner ◽  
Gerhard Steger

Abstract To defend against invading pathogens, plants possess RNA silencing mechanisms involving small RNAs (miRNAs, siRNAs). Also viroids – plant infectious, non-coding, unencapsidated RNA – cause the production of viroid-specific small RNAs (vsRNA), but viroids do escape the cytoplasmic silencing mechanism. Viroids with minor sequence variations can produce different symptoms in infected plants, suggesting an involvement of vsRNAs in symptom production. We analyzed by deep sequencing the spectrum of vsRNAs induced by the PSTVd strain AS1, which causes strong symptoms such as dwarfing and necrosis upon infection of tomato plants cv Rutgers. Indeed, vsRNAs found with highest frequency mapped to the pathogenicity-modulating domain of PSTVd, supporting an involvement of vsRNAs in symptom production. Furthermore, in PSTVd AS1-infected plants the accumulation of some endogenous miRNAs, which are involved in leaf development via regulation of transcription factors, is suppressed. The latter finding supports the hypothesis that a miRNA-dependent (mis)regula-tion of transcription factors causes the viroid symptoms.


2021 ◽  
Vol 22 (7) ◽  
pp. 3725
Author(s):  
Beatriz Navarro ◽  
Andreas Gisel ◽  
Pedro Serra ◽  
Michela Chiumenti ◽  
Francesco Di Serio ◽  
...  

Viroids are infectious non-coding RNAs that infect plants. During infection, viroid RNAs are targeted by Dicer-like proteins, generating viroid-derived small RNAs (vd-sRNAs) that can guide the sequence specific cleavage of cognate host mRNAs via an RNA silencing mechanism. To assess the involvement of these pathways in pathogenesis associated with nuclear-replicating viroids, high-throughput sequencing of sRNAs and degradome analysis were carried out on tomato and Nicotiana benthamiana plants infected by potato spindle tuber viroid (PSTVd). Both hosts develop similar stunting and leaf curling symptoms when infected by PSTVd, thus allowing comparative analyses. About one hundred tomato mRNAs potentially targeted for degradation by vd-sRNAs were initially identified. However, data from biological replicates and comparisons between mock and infected samples reduced the number of bona fide targets—i.e., those identified with high confidence in two infected biological replicates but not in the mock controls—to only eight mRNAs that encode proteins involved in development, transcription or defense. Somewhat surprisingly, results of RT-qPCR assays revealed that the accumulation of only four of these mRNAs was inhibited in the PSTVd-infected tomato. When these analyses were extended to mock inoculated and PSTVd-infected N. benthamiana plants, a completely different set of potential mRNA targets was identified. The failure to identify homologous mRNA(s) targeted by PSTVd-sRNA suggests that different pathways could be involved in the elicitation of similar symptoms in these two species. Moreover, no significant modifications in the accumulation of miRNAs and in the cleavage of their targeted mRNAs were detected in the infected tomato plants with respect to the mock controls. Taken together, these data suggest that stunting and leaf curling symptoms induced by PSTVd are elicited by a complex plant response involving multiple mechanisms, with RNA silencing being only one of the possible components.


Viruses ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 98 ◽  
Author(s):  
Fiona Constable ◽  
Grant Chambers ◽  
Lindsay Penrose ◽  
Andrew Daly ◽  
Joanne Mackie ◽  
...  

Pospiviroid species are transmitted through capsicum and tomato seeds. Trade in these seeds represents a route for the viroids to invade new regions, but the magnitude of this hazard has not been adequately investigated. Since 2012, tomato seed lots sent to Australia have been tested for pospiviroids before they are released from border quarantine, and capsicum seed lots have been similarly tested in quarantine since 2013. Altogether, more than 2000 seed lots have been tested. Pospiviroids were detected in more than 10% of the seed lots in the first years of mandatory testing, but the proportion of lots that were infected declined in subsequent years to less than 5%. Six pospiviroid species were detected: Citrus exocortis viroid, Columnea latent viroid, Pepper chat fruit viroid, Potato spindle tuber viroid, Tomato chlorotic dwarf viroid and Tomato apical stunt viroid. They were detected in seed lots exported from 18 countries from every production region. In many seed lots, the detectable fraction (prevalence) of infected seeds was estimated to be very small, as low as 6 × 10−5 (~1 in 16,000; CI 5 × 10−6 to 2.5 × 10−4) for some lots. These findings raise questions about seed production practices, and the study indicates the geographic distributions of these pathogens are uncertain, and there is a continuing threat of invasion.


2021 ◽  
Author(s):  
April M MacIntyre ◽  
Valerian Meline ◽  
Zachary Gorman ◽  
Steven P Augustine ◽  
Carolyn J Dye ◽  
...  

Ralstonia solanacearum causes plant bacterial wilt disease, leading to severe crop losses. Xylem sap from R. solanacearum-infected tomato is enriched in host produced trehalose. Water stressed plants accumulate the disaccharide trehalose, which increases drought tolerance via abscisic acid (ABA) signaling networks. Because infected plants have reduced water flow, we hypothesized that bacterial wilt physiologically mimics drought stress, which trehalose could mitigate. Transcriptomic responses of susceptible vs. resistant tomato plants to R. solanacearum infection revealed differential expression of drought-associated genes, including those involved in ABA and trehalose metabolism. ABA was enriched in xylem sap from R. solanacearum-infected plants. Treating roots with ABA lowered stomatal conductance and reduced R. solanacearum stem colonization. Treating roots with trehalose increased ABA in xylem sap and reduced plant water use by reducing stomatal conductance and temporarily improving water use efficiency. Further, trehalose-treated plants were more resistant to bacterial wilt disease. Trehalose treatment also upregulated expression of salicylic acid (SA)-dependent defense genes, increased xylem sap levels of SA and other antimicrobial compounds, and increased wilt resistance of SA-insensitive NahG tomato plants. Additionally, trehalose treatment increased xylem concentrations of jasmonic acid and related oxylipins. Together, these data show that exogenous trehalose reduced both water stress and bacterial wilt disease and triggered systemic resistance. This suite of responses revealed unexpected linkages between plant responses to biotic and abiotic stress and suggests that that R. solanacearum-infected tomato plants produce more trehalose to improve water use efficiency and increase wilt disease resistance. In turn, R. solanacearum degrades trehalose as a counter-defense.


2020 ◽  
Vol 18 (4) ◽  
pp. e10SC05
Author(s):  
Ivana Stankovic ◽  
Ana Vucurovic ◽  
Katarina Zecevic ◽  
Branka Petrovic ◽  
Danijela Ristic ◽  
...  

Aim of study: To report the occurrence of Pepino mosaic virus (PepMV) on tomato in Serbia and to genetically characterize Serbian PepMV isolates.Area of study: Tomato samples showing virus-like symptoms were collected in the Bogojevce locality (Jablanica District, Serbia).Material and methods: Collected tomato samples were assayed by DAS-ELISA using antisera against eight economically important or quarantine tomato viruses. Three selected isolates of naturally infected tomato plants were mechanically transmitted to tomato ‘Novosadski jabučar’ seedlings. For confirmation of PepMV infection, RT-PCR was performed using specific primers PepMV TGB F/PepMV UTR R. Maximum-likelihood phylogenetic tree was constructed with 47 complete CP gene sequences of PepMV to determine the genetic relationship of Serbian PepMV isolates with those from other parts of the world.Main results: The results of DAS-ELISA indicated the presence of PepMV in all tested samples. Mechanically inoculated ‘Novosadski jabučar’ seedlings expressed yellow spots and light and dark green patches, bubbling, and curled leaves. All tested tomato plants were RT-PCR positive for the presence of PepMV. The CP sequence analysis revealed that the Serbian PepMV isolates were completely identical among themselves and shared the highest nucleotide identity of 95.1% (99.2% aa identity) with isolate from Spain (FJ263341). Phylogenetic analysis showed clustering of the Serbian PepMV isolates into CH2 strain, but they formed separate subgroup within CH2 strain.Research highlights: This is the first data of the presence of PepMV in protected tomato production in Serbia. Considering increased incidence and rapid spread in Europe, the presence of PepMV on tomato could therefore represent serious threat to this valuable crop in Serbia.


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