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Gustaaf A De Zoeten - One of the best experts on this subject based on the ideXlab platform.
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pea Enation mosaic and the vagaries of a plant virus
Advances in Virus Research, 2001Co-Authors: Gustaaf A De Zoeten, Jihad S SkafAbstract:Publisher Summary This chapter discusses the variety of origins that can be inferred from the genetic information now available for the many single stranded-RNA viruses and for the many that are awaiting discovery. The word “vagaries” is used to convey the curious and unusual nature of Pea Enation mosaic virus (PEMV) and a group of possibly eight to twelve viruses that exhibit similar lifestyles. The first reference to the “mosaic disease of the sweet pea” was made in 1914. Besides the mosaic symptoms, PEMV can produce hyperplastic outgrowths (Enations) on the underside of infected leaves. The virus is mechanically as well as aphid transmissible. PEMV infections are recognized five to seven days after inoculation by the downward curling of the leaves of inoculated pea plants, followed by the appearance of chlorotic and translucent spots on the leaves. Symptoms are variable depending on the host, the virus isolate, and the environment. PEMV infections are accompanied by diagnostic and characteristic cytopathological effects that are reminiscent of those caused by the members of the Luteoviridae.
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mutational evidence that the vpg is involved in the replication and not the movement of pea Enation mosaic virus 1
Journal of General Virology, 2000Co-Authors: Jihad S Skaf, Marilou H Schultz, Hisae Hirata, Gustaaf A De ZoetenAbstract:Pea Enation mosaic disease is caused by an obligatory association between the enamovirus Pea Enation mosaic virus-1 (PEMV-1) and the umbravirus Pea Enation mosaic virus-2(PEMV-2). Encapsidated RNAs 1 and 2 are covalently linked to a 3138 Da VPg encoded by the RNA of PEMV-1. To determine the role of the VPg in the pathogenicity of PEMV (PEMV-1+PEMV-2), the infectivity of clones with mutations in key amino acids in the VPg was evaluated in protoplasts and in plants. Using quantitative, real-time RT–PCR, we concluded that the inability of certain mutants to infect plants was due to their replicative (and not their movement) incompetence. Mutant clones that produced delayed and less severe infections accumulated 10- to 100-fold less RNA-1 compared to WT-RNA-1 both in plants and in protoplasts. The RNAs of clones that produced WT-like infections accumulated to levels similar to those of WT-PEMV. Also, we demonstrate that the severity of symptoms produced by WT-PEMV is proportional to the amount of RNA-1 that accumulates in infected plants and seems to be independent of the amount of RNA-2. A dual role for the VPg in the pathogenicity of PEMV is proposed.
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pea Enation mosaic enamovirus properties and aphid transmission
1996Co-Authors: S A Demler, Gustaaf A De Zoeten, G Adam, K F HarrisAbstract:Pea Enation mosaic enamovirus (PEMV) has long been recognized to have a unique combination of properties and has been assigned to a monotypic group (Harrison et al., 1971), now given the generic name Enamovirus (de Zoeten and Demler, 1995). The generic characters include a bipartite, plussense, single-stranded RNA (ssRNA) genome, both RNA species (RNA-1 and RNA-2) being needed to establish a systemic infection and each being encapsidated in separate morphologically distinct icosahedral particles. The virus is transmissible by aphids in the persistent (circulative) manner and by mechanical inoculation. Some isolates also contain a nonessential third RNA species, designated RNA-3.
Jihad S Skaf - One of the best experts on this subject based on the ideXlab platform.
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pea Enation mosaic and the vagaries of a plant virus
Advances in Virus Research, 2001Co-Authors: Gustaaf A De Zoeten, Jihad S SkafAbstract:Publisher Summary This chapter discusses the variety of origins that can be inferred from the genetic information now available for the many single stranded-RNA viruses and for the many that are awaiting discovery. The word “vagaries” is used to convey the curious and unusual nature of Pea Enation mosaic virus (PEMV) and a group of possibly eight to twelve viruses that exhibit similar lifestyles. The first reference to the “mosaic disease of the sweet pea” was made in 1914. Besides the mosaic symptoms, PEMV can produce hyperplastic outgrowths (Enations) on the underside of infected leaves. The virus is mechanically as well as aphid transmissible. PEMV infections are recognized five to seven days after inoculation by the downward curling of the leaves of inoculated pea plants, followed by the appearance of chlorotic and translucent spots on the leaves. Symptoms are variable depending on the host, the virus isolate, and the environment. PEMV infections are accompanied by diagnostic and characteristic cytopathological effects that are reminiscent of those caused by the members of the Luteoviridae.
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mutational evidence that the vpg is involved in the replication and not the movement of pea Enation mosaic virus 1
Journal of General Virology, 2000Co-Authors: Jihad S Skaf, Marilou H Schultz, Hisae Hirata, Gustaaf A De ZoetenAbstract:Pea Enation mosaic disease is caused by an obligatory association between the enamovirus Pea Enation mosaic virus-1 (PEMV-1) and the umbravirus Pea Enation mosaic virus-2(PEMV-2). Encapsidated RNAs 1 and 2 are covalently linked to a 3138 Da VPg encoded by the RNA of PEMV-1. To determine the role of the VPg in the pathogenicity of PEMV (PEMV-1+PEMV-2), the infectivity of clones with mutations in key amino acids in the VPg was evaluated in protoplasts and in plants. Using quantitative, real-time RT–PCR, we concluded that the inability of certain mutants to infect plants was due to their replicative (and not their movement) incompetence. Mutant clones that produced delayed and less severe infections accumulated 10- to 100-fold less RNA-1 compared to WT-RNA-1 both in plants and in protoplasts. The RNAs of clones that produced WT-like infections accumulated to levels similar to those of WT-PEMV. Also, we demonstrate that the severity of symptoms produced by WT-PEMV is proportional to the amount of RNA-1 that accumulates in infected plants and seems to be independent of the amount of RNA-2. A dual role for the VPg in the pathogenicity of PEMV is proposed.
Petr Ilik - One of the best experts on this subject based on the ideXlab platform.
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reactive oxygen and nitrogen species and hormone signalling in systemic infection of pea by pea Enation mosaic virus
Plant protection science, 2018Co-Authors: Helena Kyselakova, Michaela Sedlařova, Martin Kubala, V Nožkova, Jana Piterkova, Lenka Luhova, Ondřej Novak, Petr IlikAbstract:Kyselakova H., Sedlařova M., Kubala M., Nožkova V., Piterkova J., Luhova L., Novak O., Ilik P. (2013): Reactive oxygen and nitrogen species and hormone signalling in systemic infection of pea by Pea Enation mosaic virus. Plant Protect. Sci., 49: 105–119. The physiological responses of pea plants during 40 days of compatible interaction with Pea Enation mosaic virus (PEMV) were evaluated. PEMV induces systemic changes in the concentration of phytohormones. At 5 days post inoculation (dpi), a simultaneous increase in abscisic acid (ABA) level and a decrease in salicylic acid (SA) level was observed, which is known to be involved in the suppression of hypersensitive reaction. In our pathosystem it preceded the virus presence in the systemic leaves. PEMV induces the accumulation of ABA, SA and Hsp70 and enhances peroxidase (POX) activity at 15 dpi, when it is already transmitted throughout the plant. The formation of Enations was preceded by a local accumulation of nitric oxide, which was followed by the appearance of reactive oxygen spe cies, mostly in the vicinity of leaf veins. Such heterogeneity suggests involvement of these molecules in the control of hyperplasia and tissue differentiation.
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Reactive oxygen and nitrogen species and hormone signalling in systemic infection of pea by Pea Enation mosaic virus
Plant Protection Science, 2013Co-Authors: Helena Kyselakova, Michaela Sedlařova, Martin Kubala, V Nožkova, Jana Piterkova, Lenka Luhova, Ondřej Novak, Petr IlikAbstract:The physiological responses of pea plants during 40 days of compatible interaction with Pea Enation mosaic virus (PEMV) were evaluated. PEMV induces systemic changes in the concentration of phytohormones. At 5 days post inoculation (dpi), a simultaneous increase in abscisic acid (ABA) level and a decrease in salicylic acid (SA) level was observed, which is known to be involved in the suppression of hypersensitive reaction. In our pathosystem it preceded the virus presence in the systemic leaves. PEMV induces the accumulation of ABA, SA and Hsp70 and enhances peroxidase (POX) activity at 15 dpi, when it is already transmitted throughout the plant. The formation of Enations was preceded by a local accumulation of nitric oxide, which was followed by the appearance of reactive oxygen species, mostly in the vicinity of leaf veins. Such heterogeneity suggests involvement of these molecules in the control of hyperplasia and tissue differentiation.
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photosynthetic alterations of pea leaves infected systemically by pea Enation mosaic virus a coordinated decrease in efficiencies of co2 assimilation and photosystem ii photochemistry
Plant Physiology and Biochemistry, 2011Co-Authors: Helena Kyselakova, Ondřej Novak, Jitka Prokopova, Jan Naus, M Navratil, D Safařova, Martina Spundova, Petr IlikAbstract:Abstract We have investigated photosynthetic changes of fully expanded pea leaves infected systemically by pea Enation mosaic virus (PEMV) that often attacks legumes particularly in northern temperate regions. A typical compatible virus–host interaction was monitored during 40 post-inoculation days (dpi). An initial PEMV-induced decrease in photosynthetic CO2 assimilation was detected at 15 dpi, when the virus appeared in the measured leaves. This decrease was not induced by stomata closure and corresponded with a decrease in the efficiency of photosystem II photochemistry (ΦPSII). Despite of a slight impairment of oxygen evolution at this stage, PSII function was not primarily responsible for the decrease in ΦPSII. Chlorophyll fluorescence imaging revealed that ΦPSII started to decrease from the leaf tip to the base. More pronounced symptoms of PEMV disease appeared at later stages, when a typical mosaic and Enations appeared in the infected leaves and oxidative damage of cell membranes was detected. From 30 dpi, a degradation of photosynthetic pigments accelerated, stomata were closing and corresponding pronounced decline in CO2 assimilation was observed. A concomitant photoprotective responses, i.e. an increase in non-photochemical quenching and accumulation of de-epoxidized xanthophylls, were also detected. Interestingly, alternative electron sinks in chloroplasts were not stimulated by PEMV infection, which is in contradiction to earlier reports dealing with virus-induced plant stresses. The presented results show that the PEMV-induced alterations in mature pea leaves accelerated leaf senescence during which a decrease in ΦPSII took place in coordinated manner with an inhibition of CO2 assimilation.
Helena Kyselakova - One of the best experts on this subject based on the ideXlab platform.
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reactive oxygen and nitrogen species and hormone signalling in systemic infection of pea by pea Enation mosaic virus
Plant protection science, 2018Co-Authors: Helena Kyselakova, Michaela Sedlařova, Martin Kubala, V Nožkova, Jana Piterkova, Lenka Luhova, Ondřej Novak, Petr IlikAbstract:Kyselakova H., Sedlařova M., Kubala M., Nožkova V., Piterkova J., Luhova L., Novak O., Ilik P. (2013): Reactive oxygen and nitrogen species and hormone signalling in systemic infection of pea by Pea Enation mosaic virus. Plant Protect. Sci., 49: 105–119. The physiological responses of pea plants during 40 days of compatible interaction with Pea Enation mosaic virus (PEMV) were evaluated. PEMV induces systemic changes in the concentration of phytohormones. At 5 days post inoculation (dpi), a simultaneous increase in abscisic acid (ABA) level and a decrease in salicylic acid (SA) level was observed, which is known to be involved in the suppression of hypersensitive reaction. In our pathosystem it preceded the virus presence in the systemic leaves. PEMV induces the accumulation of ABA, SA and Hsp70 and enhances peroxidase (POX) activity at 15 dpi, when it is already transmitted throughout the plant. The formation of Enations was preceded by a local accumulation of nitric oxide, which was followed by the appearance of reactive oxygen spe cies, mostly in the vicinity of leaf veins. Such heterogeneity suggests involvement of these molecules in the control of hyperplasia and tissue differentiation.
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Reactive oxygen and nitrogen species and hormone signalling in systemic infection of pea by Pea Enation mosaic virus
Plant Protection Science, 2013Co-Authors: Helena Kyselakova, Michaela Sedlařova, Martin Kubala, V Nožkova, Jana Piterkova, Lenka Luhova, Ondřej Novak, Petr IlikAbstract:The physiological responses of pea plants during 40 days of compatible interaction with Pea Enation mosaic virus (PEMV) were evaluated. PEMV induces systemic changes in the concentration of phytohormones. At 5 days post inoculation (dpi), a simultaneous increase in abscisic acid (ABA) level and a decrease in salicylic acid (SA) level was observed, which is known to be involved in the suppression of hypersensitive reaction. In our pathosystem it preceded the virus presence in the systemic leaves. PEMV induces the accumulation of ABA, SA and Hsp70 and enhances peroxidase (POX) activity at 15 dpi, when it is already transmitted throughout the plant. The formation of Enations was preceded by a local accumulation of nitric oxide, which was followed by the appearance of reactive oxygen species, mostly in the vicinity of leaf veins. Such heterogeneity suggests involvement of these molecules in the control of hyperplasia and tissue differentiation.
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photosynthetic alterations of pea leaves infected systemically by pea Enation mosaic virus a coordinated decrease in efficiencies of co2 assimilation and photosystem ii photochemistry
Plant Physiology and Biochemistry, 2011Co-Authors: Helena Kyselakova, Ondřej Novak, Jitka Prokopova, Jan Naus, M Navratil, D Safařova, Martina Spundova, Petr IlikAbstract:Abstract We have investigated photosynthetic changes of fully expanded pea leaves infected systemically by pea Enation mosaic virus (PEMV) that often attacks legumes particularly in northern temperate regions. A typical compatible virus–host interaction was monitored during 40 post-inoculation days (dpi). An initial PEMV-induced decrease in photosynthetic CO2 assimilation was detected at 15 dpi, when the virus appeared in the measured leaves. This decrease was not induced by stomata closure and corresponded with a decrease in the efficiency of photosystem II photochemistry (ΦPSII). Despite of a slight impairment of oxygen evolution at this stage, PSII function was not primarily responsible for the decrease in ΦPSII. Chlorophyll fluorescence imaging revealed that ΦPSII started to decrease from the leaf tip to the base. More pronounced symptoms of PEMV disease appeared at later stages, when a typical mosaic and Enations appeared in the infected leaves and oxidative damage of cell membranes was detected. From 30 dpi, a degradation of photosynthetic pigments accelerated, stomata were closing and corresponding pronounced decline in CO2 assimilation was observed. A concomitant photoprotective responses, i.e. an increase in non-photochemical quenching and accumulation of de-epoxidized xanthophylls, were also detected. Interestingly, alternative electron sinks in chloroplasts were not stimulated by PEMV infection, which is in contradiction to earlier reports dealing with virus-induced plant stresses. The presented results show that the PEMV-induced alterations in mature pea leaves accelerated leaf senescence during which a decrease in ΦPSII took place in coordinated manner with an inhibition of CO2 assimilation.
Leon Otten - One of the best experts on this subject based on the ideXlab platform.
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morphological analysis of the 6b oncogene induced Enation syndrome
Planta, 2016Co-Authors: Ke Chen, Leon OttenAbstract:Main conclusion The T-DNA 6b oncogene induces complex and partly unprecedented phenotypic changes in tobacco stems and leaves, which result from hypertrophy and hyperplasia with ectopic spot-like, ridge-like and sheet-like meristems. The Agrobacterium T-DNA oncogene 6b causes complex growth changes in tobacco including Enations; this unusual phenotype has been called “6b Enation syndrome”. A detailed morphological and anatomical analysis of the aerial part of Nicotiana tabacum plants transformed with a dexamethasone-inducible dex-T-6b gene revealed several striking growth phenomena. Among these were: uniform growth of ectopic photosynthetic cells on the abaxial leaf side, gutter-like petioles with multiple parallel secondary veins, ectopic leaf primordia emerging behind large glandular trichomes, corniculate structures emerging from distal ends of secondary veins, pin-like structures with remarkable branching patterns, ectopic vascular strands in midveins and petioles extending down along the stem, epiascidia and hypoascidia, double Enations and complete inhibition of leaf outgrowth. Ectopic stipule-like leaves and inverted leaves were found at the base of the petioles. Epinastic and hyponastic growth of petioles and midveins yielded complex but predictable leaf folding patterns. Detailed anatomical analysis of over sixty different 6b-induced morphological changes showed that the different modifications are derived from hypertrophy and abaxial hyperplasia, with ectopic photosynthetic cells forming spot-like, ridge-like and sheet-like meristems and ectopic vascular strands forming regular patterns in midveins, petioles and stems. Part of the Enation syndrome is due to an unknown phloem-mobile Enation factor. Graft experiments showed that the 6b mRNA is mobile and could be the Enation factor. Our work provides a better insight in the basic effects of the 6b oncogene.
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the agrobacterium oncogene ab 6b causes a graft transmissible Enation syndrome in tobacco
Plant Molecular Biology, 2003Co-Authors: Anne Helfer, Bernadette Clement, Pierre Michler, Leon OttenAbstract:Agrobacterium 6b oncogenes induce tumours and modify plant growth in various ways. Here we show that the AB-6b gene from strain AB4 placed under 2x35S promoter control (2x35S-AB-6b) induces a complex Enation syndrome in transgenic Nicotiana tabacum plants, that also occurs in a few rare cases of genetic Enations. In Arabidopsis thaliana, 2x35S-AB-6b induced radially symmetrical tubes on the abaxial side of the leaves, which must therefore be considered as the Arabidopsis equivalents of Enations on other plant species. Tobacco and Arabidopsis 2x35S-AB-6b leaves contained small, supernumerary densely packed cells between the spongy mesophyll and the abaxial epidermis, close to vascular strands arising at an early stage of leaf development. On tobacco, the 2x35S-AB-6b Enation syndrome could be transmitted across graft junctions to growing tissues of untransformed plants, both acropetally and basipetally. We propose that the AB-6b gene encodes the synthesis of one or more Enation factor(s) that are transported by the phloem and modify the growth of developing tissues.