Movement of Potato Spindle Tuber Viroid Reveals Regulatory Points of Phloem-Mediated RNA Traffic

Zhu, Yali; Qi, Yijun; Yan, Xun; Owens, Robert A.; Ding, Biao

doi:10.1104/pp.006403

Cited by 98 publications

(96 citation statements)

References 52 publications

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“…Alternatively, the modified CCR could confer the pathogenic effect at the nucleotide sequence level. We showed previously that the computed PSTVd secondary structure was not altered by the U257A substitution Zhu et al, 2002). To verify the computed data, we used temperature gradient gel electrophoresis (TGGE) (Figure 3A) to analyze the denaturation profiles of PSTVd Int U257A and PSTVd Int .…”

Section: The U257a Substitution In Pstvd Int Was Required Specificallmentioning

confidence: 83%

“…We showed previously that two independent mutations in loop E of CCR, C259U and U257A, converted PSTVd Int to tobacco infectious variants PSTVd Int C259U and PSTVd Int U257A, respectively ( Figure 1B) Zhu et al, 2002). We were interested in knowing whether these mutations would alter infectivity in tomato, a convenient experimental host for the study of viroid symptoms.…”

Section: The Nucleotide Substitution U257a Converted Pstvd Int To a Lmentioning

confidence: 99%

“…(B) Selected portions of PSTVd Int , PSTVd Int C259U, and PSTVd Int U257A containing nucleotides of loop E. The nucleotide substitutions C259U and U257A that give rise to the latter two variants are indicated by arrows. (Figure adapted from Zhu et al, 2002. ) Cotyledons of 6-day-old seedlings were inoculated with 100 ng/L PSTVd transcripts.…”

Section: The Nucleotide Substitution U257a Converted Pstvd Int To a Lmentioning

confidence: 99%

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Inhibition of Cell Growth and Shoot Development by a Specific Nucleotide Sequence in a Noncoding Viroid RNA

Qi¹,

Ding²

2003

Plant Cell

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129

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Viroids are small noncoding and infectious RNAs that replicate autonomously and move systemically throughout an infected plant. The RNAs of the family Pospiviroidae contain a central conserved region (CCR) that has long been thought to be involved in replication. Here, we report that the CCR of Potato spindle tuber viroid (PSTVd) also plays a role in pathogenicity. A U257A change in the CCR converted the intermediate strain PSTVd Int to a lethal strain that caused severe growth stunting and premature death of infected plants. PSTVd with nucleotide U257 changed to C or G did not cause such symptoms. The pathogenic effect of the U257A substitution was abolished by a C259U substitution in the same RNA. Analyses of the pathogenic effects of the U257A substitution in three other PSTVd variants established A257 as a new pathogenicity determinant that functions independently and synergistically with the classic pathogenicity domain. The U257A substitution did not alter PSTVd secondary structure, replication levels, or tissue tropism. The stunted growth of PSTVd Int U257A-infected tomato plants resulted from restricted cell expansion but not cell division or differentiation. This was correlated positively with the downregulated expression of an expansin gene, LeExp2 . Our results demonstrate that specific nucleotides in a noncoding, pathogenic RNA have a profound effect in altering distinct cellular responses, which then lead to well-defined alterations in plant growth and developmental patterns. The feasibility of correlating viroid RNA sequence/structure with the altered expression of specific host genes, cellular processes, and developmental patterns makes viroid infection a valuable system in which to investigate host factors for symptom expression and perhaps also to characterize the mechanisms of RNA regulation of gene expression in plants.

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Section: The U257a Substitution In Pstvd Int Was Required Specificallmentioning

confidence: 83%

Section: The Nucleotide Substitution U257a Converted Pstvd Int To a Lmentioning

confidence: 99%

Section: The Nucleotide Substitution U257a Converted Pstvd Int To a Lmentioning

confidence: 99%

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Inhibition of Cell Growth and Shoot Development by a Specific Nucleotide Sequence in a Noncoding Viroid RNA

Qi¹,

Ding²

2003

Plant Cell

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129

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“…It has been suggested previously that PSTVd could have a motif mediating trafficking (Ding et al, 1997) and that the phloem may have a factor able to recognize and traffic PSTVd into selective sink organs. Furthermore, phloem entry and exit appear to be differently regulated (Zhu et al, 2001(Zhu et al, , 2002. Further work with PSTVd mutants defined a bipartite trafficking motif, one part formed in the T R domain (U201) and the other in the canonical P domain (U309 and U47/A313).…”

Section: Discussionmentioning

confidence: 99%

Effect of citrus hosts on the generation, maintenance and evolutionary fate of genetic variability of citrus exocortis viroid

Bernad

Duran-Vila

Elena

2009

Journal of General Virology

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Citrus exocortis viroid (CEVd) populations are composed of closely related haplotypes whose frequencies in the population result from the equilibrium between mutation, selection and genetic drift. The genetic diversity of CEVd populations infecting different citrus hosts was studied by comparing populations recovered from infected trifoliate orange and sour orange seedling trees after 10 years of evolution, with the ancestral population maintained for the same period in the original host, Etrog citron. Furthermore, populations isolated from these trifoliate orange and sour orange trees were transmitted back to Etrog citron plants and the evolution of their mutant spectra was studied. The results indicate that (i) the amount and composition of the within-plant genetic diversity generated varies between these two hosts and is markedly different from that which is characteristic of the original Etrog citron host and (ii) the genetic diversity found after transmitting back to Etrog citron is indistinguishable from that which is characteristic of the ancestral Etrog citron population, regardless of the citrus plant from which the evolved populations were isolated. The relationship between the CEVd populations from Etrog citron and trifoliate orange, both sensitive hosts, and those from sour orange, which is a tolerant host, is discussed. INTRODUCTIONViroids are small plant pathogens consisting of a naked single-stranded circular RNA molecule of 246-475 nt, that do not encode any proteins but are endowed with autonomous replication in their host plants. It is very likely that viroids have been co-evolving with their hosts since their origin, although many of them show a wide host range. The identification of viroids in wild and cultivated plants, as symptomless carriers, suggests that certain hosts may act as natural viroid reservoirs (Diener, 1995).Viroids are taxonomically classified into two families, Pospiviroidae and Avsunviroidae (Elena et al., 1991). These families mainly differ in three characteristics. First, all pospiviroidae present a central conserved region (CCR) in their rod-like secondary structure, whereas the avsunviroidae lack such a region. Second, the pospiviroidae rely on cellular factors to process their multimeric replication intermediates into unit-length molecules, while the avsunviroidae present hammerhead ribozyme structures that are able to self-cleave the multimeric forms. Third, the pospiviroidae replicate in the nucleus whereas the avsunviroidae replicate in the chloroplast (reviewed by Flores et al., 2005).Like most RNA and some DNA viruses, viroids replicate within their hosts as polymorphic populations composed of closely related sequence variants generally distributed around a predominant one. This polymorphic population structure arises as a result of (i) the high mutation rates inherent to the cellular DNA-dependent RNA polymerases involved in viroid replication subverted to replicate an RNA template and (ii) the diverse and fluctuating selective pressures imposed by the different ...

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“…Systemic infection involves both the movement of viroid RNA from cell-to-cell through the plasmodesmata, and long distance movement paralleling the transport of photosynthate through the phloem. For Potato spindle tuber viroid (PSTVd), movement through the phloem involves the interaction with host proteins [4][5][6].…”

mentioning

confidence: 99%

Nuclear targeting by fragmentation of the Potato spindle tuber viroid genome

Abraitienė

Zhao

Hammond

2008

Biochemical and Biophysical Research Communications

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Movement of Potato Spindle Tuber Viroid Reveals Regulatory Points of Phloem-Mediated RNA Traffic

Cited by 98 publications

References 52 publications

Inhibition of Cell Growth and Shoot Development by a Specific Nucleotide Sequence in a Noncoding Viroid RNA

Inhibition of Cell Growth and Shoot Development by a Specific Nucleotide Sequence in a Noncoding Viroid RNA

Effect of citrus hosts on the generation, maintenance and evolutionary fate of genetic variability of citrus exocortis viroid

Nuclear targeting by fragmentation of the Potato spindle tuber viroid genome

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