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Genetic and histological studies on the delayed systemic movement of Tobacco Mosaic Virus in Arabidopsis thaliana.

Serrano C, González-Cruz J, Jauregui F, Medina C, Mancilla P, Matus JT, Arce-Johnson P - BMC Genet. (2008)

Bottom Line: Electron microscopy studies following the virion's route in stems of Col-0 infected plants showed the presence of curved structures, instead of the typical rigid rods of TMV-U1.This was not observed in the case of TMV-U1 infection in Uk-4, where the observed virions have the typical rigid rod morphology.The presence of defectively assembled virions observed by electron microscopy in vascular tissue of Col-0 infected plants correlates with a recessive delayed systemic movement trait of TMV-U1 in this ecotype.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Casilla 114-D. Santiago, Chile. clserran@puc.cl

ABSTRACT

Background: Viral infections and their spread throughout a plant require numerous interactions between the host and the virus. While new functions of viral proteins involved in these processes have been revealed, current knowledge of host factors involved in the spread of a viral infection is still insufficient. In Arabidopsis thaliana, different ecotypes present varying susceptibilities to Tobacco mosaic virus strain U1 (TMV-U1). The rate of TMV-U1 systemic movement is delayed in ecotype Col-0 when compared with other 13 ecotypes.We followed viral movement through vascular tissue in Col-0 plants by electronic microscopy studies. In addition, the delay in systemic movement of TMV-U1 was genetically studied.

Results: TMV-U1 reaches apical leaves only after 18 days post rosette inoculation (dpi) in Col-0, whereas it is detected at 9 dpi in the Uk-4 ecotype. Genetic crosses between Col-0 and Uk-4 ecotypes, followed by analysis of viral movement in F1 and F2 populations, revealed that this delayed movement correlates with a recessive, monogenic and nuclear locus. The use of selected polymorphic markers showed that this locus, denoted DSTM1 (Delayed Systemic Tobamovirus Movement 1), is positioned on the large arm of chromosome II. Electron microscopy studies following the virion's route in stems of Col-0 infected plants showed the presence of curved structures, instead of the typical rigid rods of TMV-U1. This was not observed in the case of TMV-U1 infection in Uk-4, where the observed virions have the typical rigid rod morphology.

Conclusion: The presence of defectively assembled virions observed by electron microscopy in vascular tissue of Col-0 infected plants correlates with a recessive delayed systemic movement trait of TMV-U1 in this ecotype.

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Systemic movement of TMV-U1 in the F2 population. Analysis of systemic movement by Western blot in several plants of the F2 population is exemplified. The TMV-U1 coat protein was detected in the inoculated rosette leaves of all plants analysed and in apical leaves of most plants. This analysis was carried out for each of the F2 plants that appear in Table 2. CP: coat protein, St: molecular weight standard, C-: negative control (non-inoculated leaves).
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Figure 4: Systemic movement of TMV-U1 in the F2 population. Analysis of systemic movement by Western blot in several plants of the F2 population is exemplified. The TMV-U1 coat protein was detected in the inoculated rosette leaves of all plants analysed and in apical leaves of most plants. This analysis was carried out for each of the F2 plants that appear in Table 2. CP: coat protein, St: molecular weight standard, C-: negative control (non-inoculated leaves).

Mentions: To confirm the crosses between Col-0 and Uk-4, polymorphic molecular markers for the five chromosomes were tested in plants from the F1 population. All F1 tested plants resulted heterozygous, confirming that the crosses were effective (not shown). Sixty plants belonging to the F1 [(♀)Uk-4 × (♂)Col-0] population and 50 plants obtained by the reciprocal crossing [(♀)Col-0 × (♂)Uk-4] were used to screen viral movement. Three rosette leaves of each plant were inoculated with TMV-U1, and samples from both apical and inoculated leaves were taken at 12 dpi. These tissues were analyzed by Western blot to detect TMV-U1 CP presence. All F1 infected plants accumulated TMV-U1 CP in the apical leaves at 12 dpi, indicating that the susceptible phenotype (Uk-4) is dominant over the "delay in systemic movement" phenotype. These F1 plants were then self-pollinated, and 277 plants of the F2 population were evaluated for TMV-U1 movement. As an example, analysis of ten F2population plants is shown in Figure 4. Accumulation of TMV-U1 CP was examined in the inoculated rosette leaves and in the systemic apical leaves. 198 plants became systemically infected at 12 dpi, while 79 showed delayed systemic movement similar to that of the Col-0 parental ecotype (Table 2). A subsequent analysis of 112 F2 plants originating from reciprocal crosses revealed that 82 were systemically infected at 12 dpi and 30 showed a delayed infection (Table 2). These results indicate that the delay in systemic TMV-U1 movement is a recessive trait, probably controlled by a single, monogenic and nuclear locus. This locus was named DSTM1 for Delayed Systemic Tobamovirus Movement 1.


Genetic and histological studies on the delayed systemic movement of Tobacco Mosaic Virus in Arabidopsis thaliana.

Serrano C, González-Cruz J, Jauregui F, Medina C, Mancilla P, Matus JT, Arce-Johnson P - BMC Genet. (2008)

Systemic movement of TMV-U1 in the F2 population. Analysis of systemic movement by Western blot in several plants of the F2 population is exemplified. The TMV-U1 coat protein was detected in the inoculated rosette leaves of all plants analysed and in apical leaves of most plants. This analysis was carried out for each of the F2 plants that appear in Table 2. CP: coat protein, St: molecular weight standard, C-: negative control (non-inoculated leaves).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2563018&req=5

Figure 4: Systemic movement of TMV-U1 in the F2 population. Analysis of systemic movement by Western blot in several plants of the F2 population is exemplified. The TMV-U1 coat protein was detected in the inoculated rosette leaves of all plants analysed and in apical leaves of most plants. This analysis was carried out for each of the F2 plants that appear in Table 2. CP: coat protein, St: molecular weight standard, C-: negative control (non-inoculated leaves).
Mentions: To confirm the crosses between Col-0 and Uk-4, polymorphic molecular markers for the five chromosomes were tested in plants from the F1 population. All F1 tested plants resulted heterozygous, confirming that the crosses were effective (not shown). Sixty plants belonging to the F1 [(♀)Uk-4 × (♂)Col-0] population and 50 plants obtained by the reciprocal crossing [(♀)Col-0 × (♂)Uk-4] were used to screen viral movement. Three rosette leaves of each plant were inoculated with TMV-U1, and samples from both apical and inoculated leaves were taken at 12 dpi. These tissues were analyzed by Western blot to detect TMV-U1 CP presence. All F1 infected plants accumulated TMV-U1 CP in the apical leaves at 12 dpi, indicating that the susceptible phenotype (Uk-4) is dominant over the "delay in systemic movement" phenotype. These F1 plants were then self-pollinated, and 277 plants of the F2 population were evaluated for TMV-U1 movement. As an example, analysis of ten F2population plants is shown in Figure 4. Accumulation of TMV-U1 CP was examined in the inoculated rosette leaves and in the systemic apical leaves. 198 plants became systemically infected at 12 dpi, while 79 showed delayed systemic movement similar to that of the Col-0 parental ecotype (Table 2). A subsequent analysis of 112 F2 plants originating from reciprocal crosses revealed that 82 were systemically infected at 12 dpi and 30 showed a delayed infection (Table 2). These results indicate that the delay in systemic TMV-U1 movement is a recessive trait, probably controlled by a single, monogenic and nuclear locus. This locus was named DSTM1 for Delayed Systemic Tobamovirus Movement 1.

Bottom Line: Electron microscopy studies following the virion's route in stems of Col-0 infected plants showed the presence of curved structures, instead of the typical rigid rods of TMV-U1.This was not observed in the case of TMV-U1 infection in Uk-4, where the observed virions have the typical rigid rod morphology.The presence of defectively assembled virions observed by electron microscopy in vascular tissue of Col-0 infected plants correlates with a recessive delayed systemic movement trait of TMV-U1 in this ecotype.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Casilla 114-D. Santiago, Chile. clserran@puc.cl

ABSTRACT

Background: Viral infections and their spread throughout a plant require numerous interactions between the host and the virus. While new functions of viral proteins involved in these processes have been revealed, current knowledge of host factors involved in the spread of a viral infection is still insufficient. In Arabidopsis thaliana, different ecotypes present varying susceptibilities to Tobacco mosaic virus strain U1 (TMV-U1). The rate of TMV-U1 systemic movement is delayed in ecotype Col-0 when compared with other 13 ecotypes.We followed viral movement through vascular tissue in Col-0 plants by electronic microscopy studies. In addition, the delay in systemic movement of TMV-U1 was genetically studied.

Results: TMV-U1 reaches apical leaves only after 18 days post rosette inoculation (dpi) in Col-0, whereas it is detected at 9 dpi in the Uk-4 ecotype. Genetic crosses between Col-0 and Uk-4 ecotypes, followed by analysis of viral movement in F1 and F2 populations, revealed that this delayed movement correlates with a recessive, monogenic and nuclear locus. The use of selected polymorphic markers showed that this locus, denoted DSTM1 (Delayed Systemic Tobamovirus Movement 1), is positioned on the large arm of chromosome II. Electron microscopy studies following the virion's route in stems of Col-0 infected plants showed the presence of curved structures, instead of the typical rigid rods of TMV-U1. This was not observed in the case of TMV-U1 infection in Uk-4, where the observed virions have the typical rigid rod morphology.

Conclusion: The presence of defectively assembled virions observed by electron microscopy in vascular tissue of Col-0 infected plants correlates with a recessive delayed systemic movement trait of TMV-U1 in this ecotype.

Show MeSH
Related in: MedlinePlus