Séverine THOIRON
Maître de conférences Université
section 66
| Équipe : |
Thèmes de recherche
Interactions plantes hôtes-plantes parasites- aspects moléculaires et cellulaires
Germination des plantes parasites en réponse à des stimulants rhizosphériques.
Parcours universitaire
- 1997 : Doctorat de l’université Montpelier II – Conséquences physiologiques et moléculaires d’une carence en fer chez le maïs. Thèse préparée au Laboratoire de Biochimie et Physiologie Moléculaire des plantes de l’INRA de Montpellier (UMR CNRS-INRA-Agro-M-UMII)
- 1990-1994 Elève de l’Ecole Normale Supérieure de Lyon (ENS Lyon)
- 1994 : DEA bases de la production végétales, université Montpellier II et magistère de Biologie Moléculaire et Cellulaire/ ENS Lyon
- 1993, 1994 : Bi-admissibilité à l’agrégation de sciences de la vie et de la terre
- 1992 : Maîtrise de Biologie Moléculaire et Cellulaire (ENS Lyon/ Univ Lyon I)
- 1991 : Licence de Biologie Moléculaire et Cellulaire (ENS Lyon/Univ Lyon I)
Publications
1 publication
Brun, Guillaume; Thoiron, Séverine; Braem, Lukas; Pouvreau, Jean-Bernard; Montiel, Grégory; Lechat, Marc-Marie; Simier, Philippe; Gevaert, Kris; Goormachtig, Sophie; Delavault, Philippe
CYP707As are effectors of karrikin and strigolactone signalling pathways in Arabidopsis thaliana and parasitic plants Article de journal
Dans: Plant Cell Environ, vol. 42, no. 9, p. 2612-2626, 2019, ISSN: 0140-7791.
@article{RN7,
title = {CYP707As are effectors of karrikin and strigolactone signalling pathways in Arabidopsis thaliana and parasitic plants},
author = {Guillaume Brun and Séverine Thoiron and Lukas Braem and Jean-Bernard Pouvreau and Grégory Montiel and Marc-Marie Lechat and Philippe Simier and Kris Gevaert and Sophie Goormachtig and Philippe Delavault},
url = {https://onlinelibrary.wiley.com/doi/10.1111/pce.13594},
doi = {10.1111/pce.13594},
issn = {0140-7791},
year = {2019},
date = {2019-01-01},
urldate = {2019-01-01},
journal = {Plant Cell Environ},
volume = {42},
number = {9},
pages = {2612-2626},
abstract = {Karrikins stimulate Arabidopsis thaliana germination, whereas parasitic weeds of the Orobanchaceae family have evolved to respond to host-exuded compounds such as strigolactones, dehydrocostus lactone, and 2-phenylethyl isothiocyanate. In Phelipanche ramosa, strigolactone-induced germination was shown to require one of the CYP707A proteins involved in abscisic acid catabolism. Here, germination and gene expression were analysed to investigate the role of CYP707As in germination of both parasitic plants and Arabidopsis upon perception of germination stimulants, after using pharmacological inhibitors and Arabidopsis mutants disrupting germination signals. CYP707A genes were up-regulated upon treatment with effective germination stimulants in both parasitic plants and Arabidopsis. Obligate parasitic plants exhibited both intensified up-regulation of CYP707A genes and increased sensitivity to the CYP707A inhibitor abscinazole-E2B, whereas Arabidopsis cyp707a mutants still positively responded to germination stimulation. In Arabidopsis, CYP707A regulation required the canonical karrikin signalling pathway KAI2/MAX2/SMAX1 and the transcription factor WRKY33. Finally, CYP707As and WRKY33 also modulated Arabidopsis root architecture in response to the synthetic strigolactone rac-GR24, and wrky33-1 exhibited a shoot hyperbranched phenotype. This study suggests that the lack of host-independent germination in obligate parasites is associated with an exacerbated CYP707A induction and that CYP707As and WRKY33 are new players involved in a variety of strigolactone/karrikin responses.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Karrikins stimulate Arabidopsis thaliana germination, whereas parasitic weeds of the Orobanchaceae family have evolved to respond to host-exuded compounds such as strigolactones, dehydrocostus lactone, and 2-phenylethyl isothiocyanate. In Phelipanche ramosa, strigolactone-induced germination was shown to require one of the CYP707A proteins involved in abscisic acid catabolism. Here, germination and gene expression were analysed to investigate the role of CYP707As in germination of both parasitic plants and Arabidopsis upon perception of germination stimulants, after using pharmacological inhibitors and Arabidopsis mutants disrupting germination signals. CYP707A genes were up-regulated upon treatment with effective germination stimulants in both parasitic plants and Arabidopsis. Obligate parasitic plants exhibited both intensified up-regulation of CYP707A genes and increased sensitivity to the CYP707A inhibitor abscinazole-E2B, whereas Arabidopsis cyp707a mutants still positively responded to germination stimulation. In Arabidopsis, CYP707A regulation required the canonical karrikin signalling pathway KAI2/MAX2/SMAX1 and the transcription factor WRKY33. Finally, CYP707As and WRKY33 also modulated Arabidopsis root architecture in response to the synthetic strigolactone rac-GR24, and wrky33-1 exhibited a shoot hyperbranched phenotype. This study suggests that the lack of host-independent germination in obligate parasites is associated with an exacerbated CYP707A induction and that CYP707As and WRKY33 are new players involved in a variety of strigolactone/karrikin responses.
1 publication
Brun, Guillaume; Braem, Lukas; Thoiron, Séverine; Gevaert, Kris; Goormachtig, Sophie; Delavault, Philippe
Seed germination in parasitic plants: what insights can we expect from strigolactone research? Article de journal
Dans: J Exp Bot, vol. 69, no. 9, p. 2265-2280, 2018, ISSN: 0022-0957.
@article{RN5,
title = {Seed germination in parasitic plants: what insights can we expect from strigolactone research?},
author = {Guillaume Brun and Lukas Braem and Séverine Thoiron and Kris Gevaert and Sophie Goormachtig and Philippe Delavault},
url = {https://watermark.silverchair.com/erx472.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAt4wggLaBgkqhkiG9w0BBwagggLLMIICxwIBADCCAsAGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQM1yniRk8_noMBOyNMAgEQgIICkQSx0NkVWTLILIUWSlmnkftHgPP-m5t-cQPJknvKituLwilM0lvjYzZ8hS9XgfOcZXtWI5s8xbpatlB8cdpZP9UIDbsBGHsUHt7S7HlpuAZMTQ45haVuNqJvyuKge5jMk7hS88X3g81iv7EI3sBpzHd2YIKMfNhaf48kbTwwrzS4DRYGNAvL4WBc-raLQpiuWzkwcigfD-aABZkBD1-gFe8IEUnOb2RkmjlUr_liOJU7PFy_Cx4vIQEP2JYFSTWPLCUjkUom_5WQQc6OEtCE9DM41tXRLSckgbL81--d43m9Fej8gsZ4BfyxtqW2HQeS-iOmIDEWFFSwij_htBntsNJyL2q_vklyiqNPmXnr7aAG5USvV7SKNyBXBLiZMhcK4LNAPAEXOmSdSzYuMfXoO0kbljSM6ht_Z5lxwGuDDEByCqSieqyirwwsSP5G7zjEwBgLyWku3qPSVQlSht3Zw5syxIR8XT1sWmvYDcKEttmpmlsNbJCFK8vfRSi8KeAAbs1zSzg17FzgpZCOkqRY5GKdESZfeVuNdyzEA5rlbuLLEKwV2LRm2RAg8b2ygsderPTNrSDDfwLwbN5VRWZF7lyhSHemRqDOnYU59ezeS882026E4kS2LpG_zwSjma0HyCHEE2GNywtVrwKfa_0_gKE1Q-OQ8INzeshP-lrHHZqa8Q4bZLCQXLfyE1qlJnLTroDX4UIpRRhA1Ildrf_lGv2vFlPxs9DzFqjLPoqsmb5cBVdv819hiJTgqzR4v-Nm2sw1H5Vp2V8l6aPIab9ijg3ZIlpm-B6VUnUsjZA5gxKdSDHHZzIQluh9wxsUc6c_WYBWNA20_EOSP9ALg-sQsplZk3VAb1WhQh7antobYSAx_A},
doi = {10.1093/jxb/erx472},
issn = {0022-0957},
year = {2018},
date = {2018-01-01},
urldate = {2018-01-01},
journal = {J Exp Bot},
volume = {69},
number = {9},
pages = {2265-2280},
abstract = {Obligate root-parasitic plants belonging to the Orobanchaceae family are deadly pests for major crops all over the world. Because these heterotrophic plants severely damage their hosts even before emerging from the soil, there is an unequivocal need to design early and efficient methods for their control. The germination process of these species has probably undergone numerous selective pressure events in the course of evolution, in that the perception of host-derived molecules is a necessary condition for seeds to germinate. Although most of these molecules belong to the strigolactones, structurally different molecules have been identified. Since strigolactones are also classified as novel plant hormones that regulate several physiological processes other than germination, the use of autotrophic model plant species has allowed the identification of many actors involved in the strigolactone biosynthesis, perception, and signal transduction pathways. Nevertheless, many questions remain to be answered regarding the germination process of parasitic plants. For instance, how did parasitic plants evolve to germinate in response to a wide variety of molecules, while autotrophic plants do not? What particular features are associated with their lack of spontaneous germination? In this review, we attempt to illustrate to what extent conclusions from research into strigolactones could be applied to better understand the biology of parasitic plants.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Obligate root-parasitic plants belonging to the Orobanchaceae family are deadly pests for major crops all over the world. Because these heterotrophic plants severely damage their hosts even before emerging from the soil, there is an unequivocal need to design early and efficient methods for their control. The germination process of these species has probably undergone numerous selective pressure events in the course of evolution, in that the perception of host-derived molecules is a necessary condition for seeds to germinate. Although most of these molecules belong to the strigolactones, structurally different molecules have been identified. Since strigolactones are also classified as novel plant hormones that regulate several physiological processes other than germination, the use of autotrophic model plant species has allowed the identification of many actors involved in the strigolactone biosynthesis, perception, and signal transduction pathways. Nevertheless, many questions remain to be answered regarding the germination process of parasitic plants. For instance, how did parasitic plants evolve to germinate in response to a wide variety of molecules, while autotrophic plants do not? What particular features are associated with their lack of spontaneous germination? In this review, we attempt to illustrate to what extent conclusions from research into strigolactones could be applied to better understand the biology of parasitic plants.
1 publication
Lechat, Marc-Marie; Brun, Guillaume; Montiel, Grégory; Véronési, Christophe; Simier, Philippe; Thoiron, Séverine; Pouvreau, Jean-Bernard; Delavault, Philippe
Seed response to strigolactone is controlled by abscisic acid-independent DNA methylation in the obligate root parasitic plant, Phelipanche ramosa L. Pomel Article de journal
Dans: J Exp Bot, vol. 66, no. 11, p. 3129-40, 2015, ISSN: 0022-0957 (Print) 0022-0957.
@article{RN22,
title = {Seed response to strigolactone is controlled by abscisic acid-independent DNA methylation in the obligate root parasitic plant, Phelipanche ramosa L. Pomel},
author = {Marc-Marie Lechat and Guillaume Brun and Grégory Montiel and Christophe Véronési and Philippe Simier and Séverine Thoiron and Jean-Bernard Pouvreau and Philippe Delavault},
url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4449535/pdf/erv119.pdf},
doi = {10.1093/jxb/erv119},
issn = {0022-0957 (Print) 0022-0957},
year = {2015},
date = {2015-01-01},
urldate = {2015-01-01},
journal = {J Exp Bot},
volume = {66},
number = {11},
pages = {3129-40},
abstract = {Seed dormancy release of the obligate root parasitic plant, Phelipanche ramosa, requires a minimum 4-day conditioning period followed by stimulation by host-derived germination stimulants, such as strigolactones. Germination is then mediated by germination stimulant-dependent activation of PrCYP707A1, an abscisic acid catabolic gene. The molecular mechanisms occurring during the conditioning period that silence PrCYP707A1 expression and regulate germination stimulant response are almost unknown. Here, global DNA methylation quantification associated with pharmacological approaches and cytosine methylation analysis of the PrCYP707A1 promoter were used to investigate the modulation and possible role of DNA methylation during the conditioning period and in the PrCYP707A1 response to GR24, a synthetic strigolactone analogue. Active global DNA demethylation occurs during the conditioning period and is required for PrCYP707A1 activation by GR24 and for subsequent seed germination. Treatment with 5-azacytidine, a DNA-hypomethylating molecule, reduces the length of the conditioning period. Conversely, hydroxyurea, a hypermethylating agent, inhibits PrCYP707A1 expression and seed germination. Methylated DNA immunoprecipitation followed by PCR experiments and bisulfite sequencing revealed that DNA demethylation particularly impacts a 78-nucleotide sequence in the PrCYP707A1 promoter. The results here demonstrate that the DNA methylation status during the conditioning period plays a crucial role independently of abscisic acid in the regulation of P. ramosa seed germination by controlling the strigolactone-dependent expression of PrCYP707A1.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Seed dormancy release of the obligate root parasitic plant, Phelipanche ramosa, requires a minimum 4-day conditioning period followed by stimulation by host-derived germination stimulants, such as strigolactones. Germination is then mediated by germination stimulant-dependent activation of PrCYP707A1, an abscisic acid catabolic gene. The molecular mechanisms occurring during the conditioning period that silence PrCYP707A1 expression and regulate germination stimulant response are almost unknown. Here, global DNA methylation quantification associated with pharmacological approaches and cytosine methylation analysis of the PrCYP707A1 promoter were used to investigate the modulation and possible role of DNA methylation during the conditioning period and in the PrCYP707A1 response to GR24, a synthetic strigolactone analogue. Active global DNA demethylation occurs during the conditioning period and is required for PrCYP707A1 activation by GR24 and for subsequent seed germination. Treatment with 5-azacytidine, a DNA-hypomethylating molecule, reduces the length of the conditioning period. Conversely, hydroxyurea, a hypermethylating agent, inhibits PrCYP707A1 expression and seed germination. Methylated DNA immunoprecipitation followed by PCR experiments and bisulfite sequencing revealed that DNA demethylation particularly impacts a 78-nucleotide sequence in the PrCYP707A1 promoter. The results here demonstrate that the DNA methylation status during the conditioning period plays a crucial role independently of abscisic acid in the regulation of P. ramosa seed germination by controlling the strigolactone-dependent expression of PrCYP707A1.
2012
Lechat, Marc-Marie; Pouvreau, Jean-Bernard; Péron, Thomas; Gauthier, Mathieu; Montiel, Grégory; Véronési, Christophe; Todoroki, Yasushi; Bizec, Bruno Le; Monteau, Fabrice; Macherel, David; Simier, Philippe; Thoiron, Séverine; Delavault, Philippe
PrCYP707A1, an ABA catabolic gene, is a key component of Phelipanche ramosa seed germination in response to the strigolactone analogue GR24 Article de journal
Dans: J Exp Bot, vol. 63, no. 14, p. 5311–5322, 2012, ISSN: 1460-2431.
@article{pmid22859674,
title = {PrCYP707A1, an ABA catabolic gene, is a key component of Phelipanche ramosa seed germination in response to the strigolactone analogue GR24},
author = {Marc-Marie Lechat and Jean-Bernard Pouvreau and Thomas Péron and Mathieu Gauthier and Grégory Montiel and Christophe Véronési and Yasushi Todoroki and Bruno Le Bizec and Fabrice Monteau and David Macherel and Philippe Simier and Séverine Thoiron and Philippe Delavault},
doi = {10.1093/jxb/ers189},
issn = {1460-2431},
year = {2012},
date = {2012-09-01},
urldate = {2012-09-01},
journal = {J Exp Bot},
volume = {63},
number = {14},
pages = {5311--5322},
abstract = {After a conditioning period, seed dormancy in obligate root parasitic plants is released by a chemical stimulus secreted by the roots of host plants. Using Phelipanche ramosa as the model, experiments conducted in this study showed that seeds require a conditioning period of at least 4 d to be receptive to the synthetic germination stimulant GR24. A cDNA-AFLP procedure on seeds revealed 58 transcript-derived fragments (TDFs) whose expression pattern changed upon GR24 treatment. Among the isolated TDFs, two up-regulated sequences corresponded to an abscisic acid (ABA) catabolic gene, PrCYP707A1, encoding an ABA 8'-hydroxylase. Using the rapid amplification of cDNA ends method, two full-length cDNAs, PrCYP707A1 and PrCYP707A2, were isolated from seeds. Both genes were always expressed at low levels during conditioning during which an initial decline in ABA levels was recorded. GR24 application after conditioning triggered a strong up-regulation of PrCYP707A1 during the first 18 h, followed by an 8-fold decrease in ABA levels detectable 3 d after treatment. In situ hybridization experiments on GR24-treated seeds revealed a specific PrCYP707A1 mRNA accumulation in the cells located between the embryo and the micropyle. Abz-E2B, a specific inhibitor of CYP707A enzymes, significantly impeded seed germination, proving to be a non-competitive antagonist of GR24 with reversible inhibitory activity. These results demonstrate that P. ramosa seed dormancy release relies on ABA catabolism mediated by the GR24-dependent activation of PrCYP707A1. In addition, in situ hybridization corroborates the putative location of cells receptive to the germination stimulants in seeds.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
After a conditioning period, seed dormancy in obligate root parasitic plants is released by a chemical stimulus secreted by the roots of host plants. Using Phelipanche ramosa as the model, experiments conducted in this study showed that seeds require a conditioning period of at least 4 d to be receptive to the synthetic germination stimulant GR24. A cDNA-AFLP procedure on seeds revealed 58 transcript-derived fragments (TDFs) whose expression pattern changed upon GR24 treatment. Among the isolated TDFs, two up-regulated sequences corresponded to an abscisic acid (ABA) catabolic gene, PrCYP707A1, encoding an ABA 8'-hydroxylase. Using the rapid amplification of cDNA ends method, two full-length cDNAs, PrCYP707A1 and PrCYP707A2, were isolated from seeds. Both genes were always expressed at low levels during conditioning during which an initial decline in ABA levels was recorded. GR24 application after conditioning triggered a strong up-regulation of PrCYP707A1 during the first 18 h, followed by an 8-fold decrease in ABA levels detectable 3 d after treatment. In situ hybridization experiments on GR24-treated seeds revealed a specific PrCYP707A1 mRNA accumulation in the cells located between the embryo and the micropyle. Abz-E2B, a specific inhibitor of CYP707A enzymes, significantly impeded seed germination, proving to be a non-competitive antagonist of GR24 with reversible inhibitory activity. These results demonstrate that P. ramosa seed dormancy release relies on ABA catabolism mediated by the GR24-dependent activation of PrCYP707A1. In addition, in situ hybridization corroborates the putative location of cells receptive to the germination stimulants in seeds.
Péron, Thomas; Véronési, Christophe; Mortreau, Eric; Pouvreau, Jean-Bernard; Thoiron, Séverine; Leduc, Nathalie; Delavault, Philippe; Simier, Philippe
Role of the sucrose synthase encoding PrSus1 gene in the development of the parasitic plant Phelipanche ramosa L. (Pomel) Article de journal
Dans: Mol Plant Microbe Interact, vol. 25, no. 3, p. 402–411, 2012, ISSN: 0894-0282.
@article{pmid22088196,
title = {Role of the sucrose synthase encoding PrSus1 gene in the development of the parasitic plant Phelipanche ramosa L. (Pomel)},
author = {Thomas Péron and Christophe Véronési and Eric Mortreau and Jean-Bernard Pouvreau and Séverine Thoiron and Nathalie Leduc and Philippe Delavault and Philippe Simier},
doi = {10.1094/MPMI-10-11-0260},
issn = {0894-0282},
year = {2012},
date = {2012-03-01},
urldate = {2012-03-01},
journal = {Mol Plant Microbe Interact},
volume = {25},
number = {3},
pages = {402--411},
abstract = {Phelipanche ramosa L. (Pomel) is a major root-parasitic weed attacking many important crops. Success in controlling this parasite is rare and a better understanding of its unique biology is needed to develop new specific control strategies. In the present study, quantitative polymerase chain reaction experiments showed that sucrose synthase encoding PrSus1 transcripts accumulate at their highest level once the parasite is connected to the host (tomato) vascular system, mainly in the parasite tubercles, which bear numerous adventitious roots. In situ hybridization experiments revealed strong PrSus1 expression in both shoot and root apices, especially in shoot apical meristems and in the vascular tissues of scale leaves and stems, and in the apical meristems and developing xylem in roots. In addition, immunolocalization experiments showed that a sucrose synthase protein co-localized with cell-wall thickening in xylem elements. These findings highlight the role of PrSus1 in the utilization of host-derived sucrose in meristematic areas and in cellulose biosynthesis in differentiating vascular elements. We also demonstrate that PrSus1 is downregulated in response to 2,3,5-triiodobenzoic acid-induced inhibition of polar auxin transport in the host stem, suggesting that PrSus1 activity in xylem maturation is controlled by host-derived auxin.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Phelipanche ramosa L. (Pomel) is a major root-parasitic weed attacking many important crops. Success in controlling this parasite is rare and a better understanding of its unique biology is needed to develop new specific control strategies. In the present study, quantitative polymerase chain reaction experiments showed that sucrose synthase encoding PrSus1 transcripts accumulate at their highest level once the parasite is connected to the host (tomato) vascular system, mainly in the parasite tubercles, which bear numerous adventitious roots. In situ hybridization experiments revealed strong PrSus1 expression in both shoot and root apices, especially in shoot apical meristems and in the vascular tissues of scale leaves and stems, and in the apical meristems and developing xylem in roots. In addition, immunolocalization experiments showed that a sucrose synthase protein co-localized with cell-wall thickening in xylem elements. These findings highlight the role of PrSus1 in the utilization of host-derived sucrose in meristematic areas and in cellulose biosynthesis in differentiating vascular elements. We also demonstrate that PrSus1 is downregulated in response to 2,3,5-triiodobenzoic acid-induced inhibition of polar auxin transport in the host stem, suggesting that PrSus1 activity in xylem maturation is controlled by host-derived auxin.
2011
Draie, Rida; Péron, Thomas; Pouvreau, Jean-Bernard; Véronési, Christophe; Jégou, Sandrine; Delavault, Philippe; Thoiron, Séverine; Simier, Philippe
Invertases involved in the development of the parasitic plant Phelipanche ramosa: characterization of the dominant soluble acid isoform, PrSAI1 Article de journal
Dans: Mol Plant Pathol, vol. 12, no. 7, p. 638–652, 2011, ISSN: 1364-3703.
@article{pmid21726369,
title = {Invertases involved in the development of the parasitic plant Phelipanche ramosa: characterization of the dominant soluble acid isoform, PrSAI1},
author = {Rida Draie and Thomas Péron and Jean-Bernard Pouvreau and Christophe Véronési and Sandrine Jégou and Philippe Delavault and Séverine Thoiron and Philippe Simier},
doi = {10.1111/j.1364-3703.2010.00702.x},
issn = {1364-3703},
year = {2011},
date = {2011-09-01},
urldate = {2011-09-01},
journal = {Mol Plant Pathol},
volume = {12},
number = {7},
pages = {638--652},
abstract = {Phelipanche ramosa L. parasitizes major crops, acting as a competitive sink for host photoassimilates, especially sucrose. An understanding of the mechanisms of sucrose utilization in parasites is an important step in the development of new control methods. Therefore, in this study, we characterized the invertase gene family in P. ramosa and analysed its involvement in plant development. Invertase-encoded cDNAs were isolated using degenerate primers corresponding to highly conserved regions of invertases. In addition to enzyme assays, gene expression was analysed using real-time quantitative reverse transcriptase-polymerase chain reaction during overall plant development. The dominant isoform was purified and sequenced using electrospray ionization-liquid chromatography-tandem mass spectrometry (ESI-LC-MS/MS). Five invertase-encoded cDNAs were thus characterized, including PrSai1 which encodes a soluble acid invertase (SAI). Of the five invertases, PrSai1 transcripts and SAI activity were dominant in growing organs. The most active invertase corresponded to the PrSai1 gene product. The purified PrSAI1 displayed low pI and optimal pH values, specificity for β-fructofuranosides and inhibition by metallic ions and competitive inhibition by fructose. PrSAI1 is a typical vacuolar SAI that is actively involved in growth following both germination and attachment to host roots. In addition, germinated seeds displayed enhanced cell wall invertase activity (PrCWI) in comparison with preconditioned seeds, suggesting the contribution of this activity in the sink strength of infected roots during the subsequent step of root penetration. Our results show that PrSAI1 and, possibly, PrCWI constitute good targets for the development of new transgenic resistance in host plants using proteinaceous inhibitors or silencing strategies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Phelipanche ramosa L. parasitizes major crops, acting as a competitive sink for host photoassimilates, especially sucrose. An understanding of the mechanisms of sucrose utilization in parasites is an important step in the development of new control methods. Therefore, in this study, we characterized the invertase gene family in P. ramosa and analysed its involvement in plant development. Invertase-encoded cDNAs were isolated using degenerate primers corresponding to highly conserved regions of invertases. In addition to enzyme assays, gene expression was analysed using real-time quantitative reverse transcriptase-polymerase chain reaction during overall plant development. The dominant isoform was purified and sequenced using electrospray ionization-liquid chromatography-tandem mass spectrometry (ESI-LC-MS/MS). Five invertase-encoded cDNAs were thus characterized, including PrSai1 which encodes a soluble acid invertase (SAI). Of the five invertases, PrSai1 transcripts and SAI activity were dominant in growing organs. The most active invertase corresponded to the PrSai1 gene product. The purified PrSAI1 displayed low pI and optimal pH values, specificity for β-fructofuranosides and inhibition by metallic ions and competitive inhibition by fructose. PrSAI1 is a typical vacuolar SAI that is actively involved in growth following both germination and attachment to host roots. In addition, germinated seeds displayed enhanced cell wall invertase activity (PrCWI) in comparison with preconditioned seeds, suggesting the contribution of this activity in the sink strength of infected roots during the subsequent step of root penetration. Our results show that PrSAI1 and, possibly, PrCWI constitute good targets for the development of new transgenic resistance in host plants using proteinaceous inhibitors or silencing strategies.
2009
de Zélicourt, Axel; Montiel, Grégory; Pouvreau, Jean-Bernard; Thoiron, Séverine; Delgrange, Sabine; Simier, Philippe; Delavault, Philippe
Susceptibility of Phelipanche and Orobanche species to AAL-toxin Article de journal
Dans: Planta, vol. 230, no. 5, p. 1047–1055, 2009, ISSN: 1432-2048.
@article{pmid19705146,
title = {Susceptibility of Phelipanche and Orobanche species to AAL-toxin},
author = {Axel de Zélicourt and Grégory Montiel and Jean-Bernard Pouvreau and Séverine Thoiron and Sabine Delgrange and Philippe Simier and Philippe Delavault},
doi = {10.1007/s00425-009-1008-1},
issn = {1432-2048},
year = {2009},
date = {2009-10-01},
urldate = {2009-10-01},
journal = {Planta},
volume = {230},
number = {5},
pages = {1047--1055},
abstract = {Fusarium and Alternaria spp. are phytopathogenic fungi which are known to be virulent on broomrapes and to produce sphinganine-analog mycotoxins (SAMs). AAL-toxin is a SAM produced by Alternaria alternata which causes the inhibition of sphinganine N-acyltransferase, a key enzyme in sphingolipid biosynthesis, leading to accumulation of sphingoid bases. These long chain bases (LCBs) are determinant in the occurrence of programmed cell death (PCD) in susceptible plants. We showed that broomrapes are sensitive to AAL-toxin, which is not common plant behavior, and that AAL-toxin triggers cell death at the apex of the radicle as well as LCB accumulation and DNA laddering. We also demonstrated that three Lag1 homologs, encoding components of sphinganine N-acyltransferase in yeast, are present in the Orobanche cumana genome and two of them are mutated leading to an enhanced susceptibility to AAL-toxin. We therefore propose a model for the molecular mechanism governing broomrape susceptibility to the fungus Alternaria alternata.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Fusarium and Alternaria spp. are phytopathogenic fungi which are known to be virulent on broomrapes and to produce sphinganine-analog mycotoxins (SAMs). AAL-toxin is a SAM produced by Alternaria alternata which causes the inhibition of sphinganine N-acyltransferase, a key enzyme in sphingolipid biosynthesis, leading to accumulation of sphingoid bases. These long chain bases (LCBs) are determinant in the occurrence of programmed cell death (PCD) in susceptible plants. We showed that broomrapes are sensitive to AAL-toxin, which is not common plant behavior, and that AAL-toxin triggers cell death at the apex of the radicle as well as LCB accumulation and DNA laddering. We also demonstrated that three Lag1 homologs, encoding components of sphinganine N-acyltransferase in yeast, are present in the Orobanche cumana genome and two of them are mutated leading to an enhanced susceptibility to AAL-toxin. We therefore propose a model for the molecular mechanism governing broomrape susceptibility to the fungus Alternaria alternata.