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International Journal of Current Microbiology and Applied Sciences (IJCMAS)
IJCMAS is now DOI (CrossRef) registered Research Journal. The DOIs are assigned to all published IJCMAS Articles.
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National Academy of Agricultural Sciences (NAAS)
NAAS Score: *5.38 (2019)
[Effective from January 1, 2019]
For more details click here

ICV 2017: 100.00
Index Copernicus ICI Journals Master List 2017 - IJCMAS--ICV 2017: 100.00
For more details click here

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PRINT ISSN : 2319-7692
Online ISSN : 2319-7706
Issues : 12 per year
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Editor-in-chief: Dr.M.Prakash
Index Copernicus ICV 2017: 100.00
NAAS RATING 2018: 5.38

Int.J.Curr.Microbiol.App.Sci.2018.7(2): 1248-1261
DOI: https://doi.org/10.20546/ijcmas.2018.702.153


Viroids and their Mode of Parasitism – A Review
Shugufta Parveen1, Sheikh Bilal1, K.A. Bhat1*, T.A. Shah1, Vaseem Yousuf2,M. Ashraf. Bhat3, F.A. Bhat1, T.A. Wani1, M.N. Mugal1 and Uzma Rahid1
1Division of plant pathology, Faculty of Agriculture Wadura, Sher- e -Kashmir University of Agricultural Sciences and Technology of Kashmir, India
2K.V.K., Budgam. Sher- e-Kashmir University of Agricultural Sciences and Technology of Kashmir, India
3Division of GPB, Faculty of Agriculture Wadura, Sher- e -Kashmir University of Agricultural Sciences and Technology of Kashmir, India
*Corresponding author
Abstract:

Viroids are plant sub viral pathogens with small, circular, single stranded and non-protein coding RNA genome that are currently known to infect only plants. These are the smallest self-replicating genetic units. These small RNAs contain all the information necessary to mediate replication, pathogenicity, intracellular and systemic trafficking. All or most of these functions likely result from direct interactions between distinct viroid RNA structural motifs and host cellular factors. The role of these motifs in overall biology of host viroid interactions have been studied in pospiviroidae and avsuniviroidae. Structural motif comprises nucleotides U43/C318 that form a small loop is required for trafficking from the bundle sheath into the phloem in Potato spindle tuber viroid (PSTVd). In Peach latent mosaic viroid (PLMVd) RNA with a specific structural motif of 12 to 13 nucleotides in left terminal folds into a hairpin, inhibits chloroplast development and results in complete albino phenotype by impairing transcription and translation of plastid rRNA and plastid encoded proteins respectively. Several experiments support that viroids trigger RNA silencing in their hosts. It is hypothesized that viroid-derived small RNAs (vd-siRNAs) targeting specific host DNA or mRNA sequences for transcriptional or posttranscriptional gene silencing respectively leads to viroid pathogenicity. Further research is needed to find out the role of all the structural motifs involved in establishment of infection, defense mechanism by plants against viroid, entry and exit in nucleus and chloroplast, participation of host proteins in specific steps replication, trafficking and molecular basis of viroid host range.


Keywords: Viroids, Viroid replication, Trafficking, RNA structural motif, RNA silencing
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How to cite this article:

Shugufta Parveen, Sheikh Bilal, K.A. Bhat, T.A. Shah, Vaseem Yousuf, M. Ashraf. Bhat, F.A. Bhat, T.A. Wani, M.N. Mugal and Uzma Rahid. 2018. Viroids and their Mode of Parasitism – A Review.Int.J.Curr.Microbiol.App.Sci. 7(2): 1248-1261. doi: https://doi.org/10.20546/ijcmas.2018.702.153