A cis Element within Flowering Locus T mRNA Determines Its Mobility and Facilitates Trafficking of Heterologous Viral RNA

ABSTRACT The Arabidopsis flowering locus T (FT) gene encodes the mobile florigen essential for floral induction. While movement of the FT protein has been shown to occur within plants, systemic spread of FT mRNA remains to be unequivocally demonstrated. Utilizing novel RNA mobility assay vectors based on two distinct movement-defective viruses, Potato virus X and Turnip crinkle virus, and an agroinfiltration assay, we demonstrate that nontranslatable FT mRNA, independent of the FT protein, moves throughout Nicotiana benthamiana and mutant Arabidopsis plants and promotes systemic trafficking of viral and green fluorescence protein RNAs. Viral ectopic expression of FT induced flowering in the short-day N. tabacum Maryland Mammoth tobacco under long-day conditions. Recombinant Potato virus X bearing FT RNA spread and established systemic infection more quickly than the parental virus. The cis-acting element essential for RNA movement was mapped to the nucleotides 1 to 102 of the FT mRNA coding sequence. These data demonstrate that a plant self-mobile RNA molecule can mediate long-distance trafficking of heterologous RNAs and raise the possibility that FT RNA, along with the FT protein, may be involved in the spread of the floral stimulus throughout the plant.

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The Helper Component-Proteinase of Sweet potato feathery mottle virus Facilitates Systemic Spread of Potato virus X in Ipomoea nil

Phytopathology ◽

10.1094/phyto.2000.90.9.944 ◽

2000 ◽

Vol 90 (9) ◽

pp. 944-950 ◽

Cited By ~ 11

Author(s):

S. Sonoda ◽

H. Koiwa ◽

K. Kanda ◽

H. Kato ◽

M. Shimono ◽

...

Keyword(s):

Sweet Potato ◽

Potato Virus ◽

Potato Virus X ◽

Mottle Virus ◽

Single Infection ◽

Long Distance ◽

Helper Component ◽

Ipomoea Nil ◽

Systemic Spread ◽

Helper Component Proteinase

When Ipomoea nil was coinfected with Sweet potato feathery mottle virus (SPFMV), a member of the genus Potyvirus, and Potato virus X (PVX) typical symptoms caused by PVX were observed on those by SPFMV on the first upper true leaves at 14 days postinoculation (dpi). On the other hand, no PVX-induced symptoms were observed on the first upper true leaves at 14 dpi when plants were infected with PVX alone. In the case of coinfection with PVX and SPFMV, PVX RNA was detected not only in the inoculated cotyledonary leaves but also in the first upper true leaves at 14 dpi. In the case of single infection with PVX, PVX RNA was detected in the inoculated cotyledonary leaves but not in the first upper true leaves at 14 dpi. The accumulation of SPFMV remained unchanged, regardless of whether the inoculum consisted of SPFMV alone or a mixture of SPFMV and PVX. Although recombinant PVX engineered to express the helper component-proteinase (HC-Pro) of SPFMV (PVX.HC) enhanced symptoms severity in Nicotiana benthamiana, PVX.HC induced the synergism characterized by an enhanced viral movement in Ipomoea nil. Immunofluorescence microscopic examination revealed that the HC-Pro was present in phloem of SPFMV-infected I. nil. These results suggest that SPFMV HC-Pro acts as an enhancer of long distance movement for PVX in I. nil.

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Functional divergence between soybean FLOWERING LOCUS T orthologues FT2a and FT5a in post-flowering stem growth

Journal of Experimental Botany ◽

10.1093/jxb/erz199 ◽

2019 ◽

Vol 70 (15) ◽

pp. 3941-3953 ◽

Cited By ~ 2

Author(s):

Ryoma Takeshima ◽

Haiyang Nan ◽

Kohei Harigai ◽

Lidong Dong ◽

Jianghui Zhu ◽

...

Keyword(s):

Floral Induction ◽

Functional Divergence ◽

Specific Interaction ◽

Reproductive Development ◽

Stem Growth ◽

Flowering Locus T ◽

Bzip Protein ◽

Regulated Expression ◽

Flowering Stem ◽

Flowering Locus

Abstract Genes in the FLOWERING LOCUS T (FT) family integrate external and internal signals to control various aspects of plant development. In soybean (Glycine max), FT2a and FT5a play a major role in floral induction, but their roles in post-flowering reproductive development remain undetermined. Ectopic overexpression analyses revealed that FT2a and FT5a similarly induced flowering, but FT5a was markedly more effective than FT2a for the post-flowering termination of stem growth. The down-regulation of Dt1, a soybean orthologue of Arabidopsis TERMINAL FLOWER1, in shoot apices in early growing stages of FT5a-overexpressing plants was concomitant with highly up-regulated expression of APETALA1 orthologues. The Dt2 gene, a repressor of Dt1, was up-regulated similarly by the overexpression of FT2a and FT5a, suggesting that it was not involved in the control of stem termination by FT5a. In addition to the previously reported interaction with FDL19, a homologue of the Arabidopsis bZIP protein FD, both FT2a and FT5a interacted with FDL12, but only FT5a interacted with FDL06. Our results suggest that FT2a and FT5a have different functions in the control of post-flowering stem growth. A specific interaction of FT5a with FDL06 may play a key role in determining post-flowering stem growth in soybean.

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Rootstock Affects Floral Induction in Citrus Engaging the Expression of the FLOWERING LOCUS T (CiFT)

Agriculture ◽

10.3390/agriculture11020140 ◽

2021 ◽

Vol 11 (2) ◽

pp. 140

Author(s):

Stefania Bennici ◽

Giuseppina Las Casas ◽

Gaetano Distefano ◽

Alessandra Gentile ◽

Giuseppe Lana ◽

...

Keyword(s):

Floral Induction ◽

Flower Induction ◽

Water Deficit Stress ◽

Flowering Locus T ◽

Expression Levels ◽

Yield Efficiency ◽

Flowering Locus ◽

The Relationship ◽

Inductive Period ◽

Swingle Citrumelo

In Citrus, flower induction represents the transition from vegetative to reproductive growth. The regulation of flower induction is mainly triggered by exposure to low temperatures and water-deficit stress, which activates the signaling cascade leading to an increased expression of the citrus orthologs of the FLOWERING LOCUS T (CiFT). In this study, the relationship between rootstock and flower induction under Mediterranean field conditions was investigated by monitoring the expression levels of the floral promoter CiFT2 in leaves of the pigmented sweet orange “Tarocco Scirè” grafted onto “C35” citrange and “Swingle” citrumelo rootstocks. The latter two are known to confer, respectively, high and low yield efficiency to the scion. In both rootstock/scion combinations, CiFT2 showed a seasonal expression with a peak during the inductive period in January triggered by cold temperature. The “Tarocco Scirè”/”C35” citrange combination showed the highest expression levels for CiFT2; this increased expression was correlated with yield and a higher number of flowers in the following spring, suggesting a significant effect of rootstocks on flower induction mediated by the overexpression of the CiFT2 gene.

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Long-Distance, Graft-Transmissible Action of Arabidopsis FLOWERING LOCUS T Protein to Promote Flowering

Plant and Cell Physiology ◽

10.1093/pcp/pcn176 ◽

2008 ◽

Vol 49 (12) ◽

pp. 1922-1922 ◽

Cited By ~ 6

Author(s):

M. Notaguchi ◽

M. Abe ◽

T. Kimura ◽

Y. Daimon ◽

T. Kobayashi ◽

...

Keyword(s):

Flowering Locus T ◽

Long Distance ◽

Flowering Locus

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Tobacco mosaic virus (TMV) and potato virus X (PVX) coat proteins confer heterologous interference to PVX and TMV infection, respectively

Journal of General Virology ◽

10.1099/vir.0.81396-0 ◽

2006 ◽

Vol 87 (4) ◽

pp. 1005-1012 ◽

Cited By ~ 16

Author(s):

A. A. Bazzini ◽

S. Asurmendi ◽

H. E. Hopp ◽

R. N. Beachy

Keyword(s):

Transgenic Plants ◽

Tobacco Mosaic Virus ◽

Mosaic Virus ◽

Potato Virus ◽

Quaternary Structure ◽

Systemic Infection ◽

Potato Virus X ◽

Coat Proteins ◽

Local Cell ◽

Cell Spread

Replication of Potato virus X (PVX) was reduced in transgenic protoplasts that accumulated wild-type coat protein (CPWT) of Tobacco mosaic virus (TMV) or a mutant CP, CPT42W, that produced highly ordered states of aggregation, including pseudovirions. This reaction is referred to as heterologous CP-mediated resistance. However, protoplasts expressing a CP mutant that abolished aggregation and did not produce pseudovirions, CPT28W, did not reduce PVX replication. Similarly, in transgenic tobacco plants producing TMV CPWT or CPT42W, there was a delay in local cell-to-cell spread of PVX infection that was not observed in CPT28W plants or in non-transgenic plants. The results suggest that the quaternary structure of the TMV CP regulates the mechanism(s) of heterologous CP-mediated resistance. Similarly, transgenic protoplasts that produced PVX CP conferred transient protection against infection by TMV RNA. Transgenic plants that accumulated PVX CP reduced the cell-to-cell spread of infection and resulted in a delay in systemic infection following inoculation with TMV or TMV RNA. Heterologous CP-mediated resistance was characterized by a brief delay in systemic infection, whilst homologous CP-mediated resistance conferred reduced or no systemic infection.

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Long-Distance, Graft-Transmissible Action of Arabidopsis FLOWERING LOCUS T Protein to Promote Flowering

Plant and Cell Physiology ◽

10.1093/pcp/pcn154 ◽

2008 ◽

Vol 49 (11) ◽

pp. 1645-1658 ◽

Cited By ~ 162

Author(s):

Michitaka Notaguchi ◽

Mitsutomo Abe ◽

Takahiro Kimura ◽

Yasufumi Daimon ◽

Toshinori Kobayashi ◽

...

Keyword(s):

Flowering Locus T ◽

Long Distance ◽

Flowering Locus

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Components of Arabidopsis Defense- and Ethylene-Signaling Pathways Regulate Susceptibility to Cauliflower mosaic virus by Restricting Long-Distance Movement

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-20-6-0659 ◽

2007 ◽

Vol 20 (6) ◽

pp. 659-670 ◽

Cited By ~ 52

Author(s):

Andrew J. Love ◽

Valérie Laval ◽

Chiara Geri ◽

Janet Laird ◽

A. Deri Tomos ◽

...

Keyword(s):

Mosaic Virus ◽

Systemic Acquired Resistance ◽

Fluorescent Protein ◽

Acquired Resistance ◽

Systemic Infection ◽

Cauliflower Mosaic Virus ◽

Virus Movement ◽

Wild Type ◽

Long Distance ◽

Systemic Spread

We analyzed the susceptibility of Arabidopsis mutants with defects in salicylic acid (SA) and jasmonic acid (JA)/ethylene (ET) signaling to infection by Cauliflower mosaic virus (CaMV). Mutants cpr1-1 and cpr5-2, in which SA-dependent defense signaling is activated constitutively, were substantially more resistant than the wild type to systemic infection, implicating SA signaling in defense against CaMV. However, SA-deficient NahG, sid2-2, eds5-1, and pad4-1 did not show enhanced susceptibility. A cpr5 eds5 double mutant also was resistant, suggesting that resistance in cpr5 may function partially independently of SA. Treatment of cpr5 and cpr5 eds5, but not cpr1, with salicyl-hydroxamic acid, an inhibitor of alternative oxidase, partially restored susceptibility to wild-type levels. Mutants etr1-1, etr1-3, and ein2-1, and two mutants with lesions in ET/JA-mediated defense, eds4 and eds8, also showed reduced virus susceptibility, demonstrating that ET-dependent responses also play a role in susceptibility. We used a green fluorescent protein (GFP)-expressing CaMV recombinant to monitor virus movement. In mutants with reduced susceptibility, cpr1-1, cpr5-2, and etr1-1, CaMV-GFP formed local lesions similar to the wild type, but systemic spread was almost completely absent in cpr1 and cpr5 and was substantially reduced in etr1-1. Thus, mutations with enhanced systemic acquired resistance or compromised ET signaling show diminished long-distance virus movement.

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