A minimum length of N gene sequence in transgenic plants is required for RNA-mediated tospovirus resistance

Microbiology ◽  
2000 ◽  
Vol 81 (1) ◽  
pp. 235-242 ◽  
Author(s):  
Fuh-Jyh Jan ◽  
Carmen Fagoaga ◽  
Sheng-Zhi Pang ◽  
Dennis Gonsalves

We showed previously that transgenic plants with the green fluorescent protein (GFP) gene fused to segments of the nucleocapsid (N) gene of tomato spotted wilt virus (TSWV) displayed post-transcriptional gene silencing of the GFP and N gene segments and resistance to TSWV. These results suggested that a chimeric transgene composed of viral gene segments might confer multiple virus resistance in transgenic plants. To test this hypothesis and to determine the minimum length of the N gene that could trans-inactivate the challenging TSWV, transgenic plants were developed that contained GFP fused with N gene segments of 24–453 bp. Progeny from these plants were challenged with: (i) a chimeric tobacco mosaic virus containing the GFP gene, (ii) a chimeric tobacco mosaic virus with GFP plus the N gene of TSWV and (iii) TSWV. A number of transgenic plants expressing the transgene with GFP fused to N gene segments from 110 to 453 bp in size were resistant to these viruses. Resistant plants exhibited post-transcriptional gene silencing. In contrast, all transgenic lines with transgenes consisting of GFP fused to N gene segments of 24 or 59 bp were susceptible to TSWV, even though the transgene was post-transcriptionally silenced. Thus, virus resistance and post-transcriptional gene silencing were uncoupled when the N gene segment was 59 bp or less. These results provide evidence that multiple virus resistance is possible through the simple strategy of linking viral gene segments to a silencer DNA such as GFP.

2000 ◽  
Vol 81 (8) ◽  
pp. 2103-2109 ◽  
Author(s):  
Fuh-Jyh Jan ◽  
Carmen Fagoaga ◽  
Sheng-Zhi Pang ◽  
Dennis Gonsalves

We showed previously that 218 and 110 bp N gene segments of tomato spotted wilt virus (TSWV) that were fused to the non-target green fluorescent protein (GFP) gene were able to confer resistance to TSWV via post-transcriptional gene silencing (PTGS). N gene segments expressed alone did not confer resistance. Apparently, the GFP DNA induced PTGS that targetted N gene segments and the incoming homologous TSWV for degradation, resulting in a resistant phenotype. These observations suggested that multiple resistance could be obtained by replacing the GFP DNA with a viral DNA that induces PTGS. The full-length coat protein (CP) gene of turnip mosaic virus (TuMV) was linked to 218 or 110 bp N gene segments and transformed into Nicotiana benthamiana. A high proportion (4 of 18) of transgenic lines with the 218 bp N gene segment linked to the TuMV CP gene were resistant to both viruses, and resistance was transferred to R2 plants. Nuclear run-on and Northern experiments confirmed that resistance was via PTGS. In contrast, only one of 14 transgenic lines with the TuMV CP linked to a 110 bp N gene segment yielded progeny with multiple resistance. Only a few R1 plants were resistant and resistance was not observed in R2 plants. These results clearly show the applicability of multiple virus resistance through the fusion of viral segments to DNAs that induce PTGS.


2008 ◽  
Vol 18 (3) ◽  
pp. 331-345 ◽  
Author(s):  
Marina Brumin ◽  
Svetlana Stukalov ◽  
Sabrina Haviv ◽  
Mookkan Muruganantham ◽  
Yoni Moskovitz ◽  
...  

2002 ◽  
Vol 14 (3) ◽  
pp. 629-639 ◽  
Author(s):  
Jean-Benoit Morel ◽  
Christian Godon ◽  
Philippe Mourrain ◽  
Christophe Béclin ◽  
Stéphanie Boutet ◽  
...  

2007 ◽  
Vol 57 (2) ◽  
pp. 123-128 ◽  
Author(s):  
Noriyuki Furutani ◽  
Noriko Yamagishi ◽  
Soh Hidaka ◽  
Yoshiaki Shizukawa ◽  
Seiji Kanematsu ◽  
...  

1994 ◽  
pp. 437-452 ◽  
Author(s):  
Fernanda de Carvalho ◽  
Wout Boerjan ◽  
Ivan Ingelbrecht ◽  
Ann Depicker ◽  
Dirk Inzé ◽  
...  

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1187
Author(s):  
Michael Wassenegger ◽  
Athanasios Dalakouras

Viroids are plant pathogenic, circular, non-coding, single-stranded RNAs (ssRNAs). Members of the Pospiviroidae family replicate in the nucleus of plant cells through double-stranded RNA (dsRNA) intermediates, thus triggering the host’s RNA interference (RNAi) machinery. In plants, the two RNAi pillars are Post-Transcriptional Gene Silencing (PTGS) and RNA-directed DNA Methylation (RdDM), and the latter has the potential to trigger Transcriptional Gene Silencing (TGS). Over the last three decades, the employment of viroid-based systems has immensely contributed to our understanding of both of these RNAi facets. In this review, we highlight the role of Pospiviroidae in the discovery of RdDM, expound the gradual elucidation through the years of the diverse array of RdDM’s mechanistic details and propose a revised RdDM model based on the cumulative amount of evidence from viroid and non-viroid systems.


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