Unexpected silencing effects from T-DNA tags in Arabidopsis

Daxinger, Lucia; Hunter, Ben; Sheikh, Mazhar; Jauvion, Vincent; Gasciolli, Virginie; Vaucheret, Hervé; Matzke, Marjori; Furner, Ian J.

doi:10.1016/j.tplants.2007.10.007

Cited by 109 publications

(105 citation statements)

References 11 publications

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“…Given the unusual splicing behavior of vha-a2 that goes along with transinactivation of the 35S promotor driving the NPTII gene on the T-DNAs used to create the SALK and other insertion collections (23), combinations of multiple insertion alleles require detailed analysis of the individual transcript levels. To our knowledge similar cases of silencing-induced exon splicing have not been reported.…”

mentioning

confidence: 99%

Arabidopsis V-ATPase activity at the tonoplast is required for efficient nutrient storage but not for sodium accumulation

Krebs

Beyhl

Görlich

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

286

335

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The productivity of higher plants as a major source of food and energy is linked to their ability to buffer changes in the concentrations of essential and toxic ions. Transport across the tonoplast is energized by two proton pumps, the vacuolar H + -ATPase (VATPase) and the vacuolar H + -pyrophosphatase (V-PPase); however, their functional relation and relative contributions to ion storage and detoxification are unclear. We have identified an Arabidopsis mutant in which energization of vacuolar transport solely relies on the activity of the V-PPase. The vha-a2 vha-a3 double mutant, which lacks the two tonoplast-localized isoforms of the membrane-integral V-ATPase subunit VHA-a, is viable but shows day-length-dependent growth retardation. Nitrate content is reduced whereas nitrate assimilation is increased in the vha-a2 vha-a3 mutant, indicating that vacuolar nitrate storage represents a major growth-limiting factor. Zinc is an essential micronutrient that is toxic at excess concentrations and is detoxified via a vacuolar Zn 2+ /H + -antiport system. Accordingly, the double mutant shows reduced zinc tolerance. In the same way the vacuolar Na + /H + -antiport system is assumed to be an important component of the system that removes sodium from the cytosol. Unexpectedly, salt tolerance and accumulation are not affected in the vhaa2 vha-a3 double mutant. In contrast, reduction of V-ATPase activity in the trans-Golgi network/early endosome (TGN/EE) leads to increased salt sensitivity. Taken together, our results show that during gametophyte and embryo development V-PPase activity at the tonoplast is sufficient whereas tonoplast V-ATPase activity is limiting for nutrient storage but not for sodium tolerance during vegetative and reproductive growth.proton-pump | pH-homeostasis | vacuole | nitrate | salt tolerance T he productivity of higher plants as a major source of food and renewable energy is linked to their ability to cope with fluctuations in essential as well as toxic ion and metabolite concentrations. In plants the large central vacuoles function as reservoirs for ions and metabolites that allow buffering of changes in nutrients as well as challenges by toxic components that plants, as sessile, photoautotrophic organisms, frequently encounter. Furthermore, vacuoles are essential for plant growth and development. Expansion of plant cells is achieved by osmotically driven water influx into the vacuole that, in combination with the cell wall, generates turgor, the driving force for hydraulic stiffness and plant growth.All vacuolar functions require massive fluxes of ions and metabolites that are channeled by a battery of vacuolar transport proteins, many of which have been well characterized physiologically, but the nature of several transporters remains to be identified (1). Among those characterized on the molecular level are, e.g., those transporting NO 3 − , Na + , and protons. Nitrate, a major plant nutrient, is accumulated and stored in the vacuole from where it can be retrieved according to metabolic deman...

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mentioning

confidence: 99%

Arabidopsis V-ATPase activity at the tonoplast is required for efficient nutrient storage but not for sodium accumulation

Krebs

Beyhl

Görlich

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

286

335

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“…Because the arf8-6 mutation is a SALK line T-DNA insertion mutation, one likely candidate is transcriptional silencing induced by the T-DNA. The T-DNAs used to generate SALK lines and several other T-DNA insertion lines carry an extraneous cauliflower mosaic virus 35S promoter that is known to transcriptionally silence 35S promoterdriven transgenes elsewhere in the plant genome (Daxinger et al, 2008).…”

Section: Resultsmentioning

confidence: 99%

Developmental Defects Mediated by the P1/HC-Pro Potyviral Silencing Suppressor Are Not Due to Misregulation of AUXIN RESPONSE FACTOR 8

et al. 2016

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“…Initial analysis of the 306/6b4/HC-Pro plant lines addressed the possibility of transcriptional gene silencing (TGS) of the three transgenes involved, all of which are under the control of the CaMV 35S promoter. This was especially important because it has been shown that T-DNA insertion mutants that carry 35S promoter sequences, such as the rav2 knockout line used in this work, can induce TGS of other 35S promoters in the genome [36] and because HC-Pro cannot suppress silencing at the transcriptional level [37,38]. RNA gel blot analysis showed that the level of HCPro mRNA was similar in all plants carrying the HC-Pro transgene (Fig.…”

Section: Rav2 Is Required For Hc-pro Suppression Of Virus Induced Genmentioning

confidence: 89%

Introduction

2016

Phytopathology in Plants

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RNA silencing is a highly conserved pathway in the network of interconnected defense responses that are activated during viral infection. As a counter-defense, many plant viruses encode proteins that block silencing, often also interfering with endogenous small RNA pathways. However, the mechanism of action of viral suppressors is not well understood and the role of host factors in the process is just beginning to emerge. Here we report that the ethylene-inducible transcription factor RAV2 is required for suppression of RNA silencing by two unrelated plant viral proteins, potyvirus HC-Pro and carmovirus P38. Using a hairpin transgene silencing system, we find that both viral suppressors require RAV2 to block the activity of primary siRNAs, whereas suppression of transitive silencing is RAV2-independent. RAV2 is also required for many HC-Pro-mediated morphological anomalies in transgenic plants, but not for the associated defects in the microRNA pathway. Whole genome tiling microarray experiments demonstrate that expression of genes known to be required for silencing is unchanged in HC-Pro plants, whereas a striking number of genes involved in other biotic and abiotic stress responses are induced, many in a RAV2-dependent manner. Among the genes that require RAV2 for induction by HC-Pro are FRY1 and CML38, genes implicated as endogenous suppressors of silencing. These findings raise the intriguing possibility that HC-Pro-suppression of silencing is not caused by decreased expression of genes that are required for silencing, but instead, by induction of stress and defense responses, some components of which interfere with antiviral silencing. Furthermore, the observation that two unrelated viral suppressors require the activity of the same factor to block silencing suggests that RAV2 represents a control point that can be readily subverted by viruses to block antiviral silencing.

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Unexpected silencing effects from T-DNA tags in Arabidopsis

Cited by 109 publications

References 11 publications

Arabidopsis V-ATPase activity at the tonoplast is required for efficient nutrient storage but not for sodium accumulation

Arabidopsis V-ATPase activity at the tonoplast is required for efficient nutrient storage but not for sodium accumulation

Developmental Defects Mediated by the P1/HC-Pro Potyviral Silencing Suppressor Are Not Due to Misregulation of AUXIN RESPONSE FACTOR 8

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