Browsing by Author "Ritter, Andres"

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    A network of stress-related genes regulates hypocotyl elongation downstream of selective auxin perception
    (2021) Rigal, Adeline; Doyle, Siamsa M.; Ritter, Andres; Raggi, Sara; Vain, Thomas; O'Brien, Jose Antonio; Goossens, Alain; Pauwels, Laurens; Robert, Stephanie
    The plant hormone auxin, a master coordinator of development, regulates hypocotyl elongation during seedling growth. We previously identified the synthetic molecule RubNeddin 1 (RN1), which induces degradation of the AUXIN/INDOLE-3-ACETIC ACID (AUX/IAA) transcriptional repressors INDOLE-3-ACETIC ACID-INDUCIBLE3 (IAA3) and IAA7 in planta and strongly promotes hypocotyl elongation. In the present study, we show that despite the structural similarity of RN1 to the synthetic auxin 2,4-dichlorophenoxyacetic-acid (2,4-D), direct treatments with these compounds in Arabidopsis (Arabidopsis thaliana) result in distinct effects, possibly due to enhanced uptake of RN1 and low-level, chronic release of 2,4-D from RN1 in planta. We confirm RN1-induced hypocotyl elongation occurs via specific TRANSPORT INHIBITOR RESISTANT1 (TIR1)/AUXIN SIGNALING F-BOX (AFB) receptor-mediated auxin signaling involving TIR1, AFB2, and AFB5. Using a transcriptome profiling strategy and candidate gene approach, we identify the genes ZINC FINGER OF ARABIDOPSIS THALIANA10 (ZAT10), ARABIDOPSIS TOXICOS EN LEVADURA31 (ATL31), and WRKY DNA-BINDING PROTEIN33 (WRKY33) as being rapidly upregulated by RN1, despite being downregulated by 2,4-D treatment. RN1-induced expression of these genes also occurs via TIR1/AFB-mediated auxin signaling. Our results suggest both hypocotyl elongation and transcription of these genes are induced by RN1 via the promoted degradation of the AUX/IAA transcriptional repressor IAA7. Moreover, these three genes, which are known to be stress-related, act in an inter-dependent transcriptional regulatory network controlling hypocotyl elongation. Together, our results suggest ZAT10, ATL31, and WRKY33 take part in a common gene network regulating hypocotyl elongation in Arabidopsis downstream of a selective auxin perception module likely involving TIR1, AFB2, and AFB5 and inducing the degradation of IAA7.
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    Herbivore-induced chemical and molecular responses of the kelps Laminaria digitata and Lessonia spicata
    (2017) Ritter, Andres; Cabioch, Lea; Brillet-Gueguen, Loraine; Corre, Erwan; Cosse, Audrey; Dartevelle, Laurence; Durufle, Harold; Fasshauer, Carina; Goulitquer, Sophie; Thomas, Francois; Correa, Juan A.; Potin, Philippe; Faugeron, Sylvain; Leblanc, Catherine
    Kelps are founding species of temperate marine ecosystems, living in intertidal coastal areas where they are often challenged by generalist and specialist herbivores. As most sessile organisms, kelps develop defensive strategies to restrain grazing damage and preserve their own fitness during interactions with herbivores. To decipher some inducible defense and signaling mechanisms, we carried out metabolome and transcriptome analyses in two emblematic kelp species, Lessonia spicata from South Pacific coasts and Laminaria digitata from North Atlantic, when challenged with their main specialist herbivores. Mass spectrometry based metabolomics revealed large metabolic changes induced in these two brown algae following challenges with their own specialist herbivores. Targeted metabolic profiling of L. spicata further showed that free fatty acid (FFA) and amino acid (AA) metabolisms were particularly regulated under grazing. An early stress response was illustrated by the accumulation of Sulphur containing amino acids in the first twelve hours of herbivory pressure. At latter time periods (after 24 hours), we observed FFA liberation and eicosanoid oxylipins synthesis likely representing metabolites related to stress. Global transcriptomic analysis identified sets of candidate genes specifically induced by grazing in both kelps. qPCR analysis of the top candidate genes during a 48-hours time course validated the results. Most of these genes were particularly activated by herbivore challenge after 24 hours, suggesting that transcriptional reprogramming could be operated at this time period. We demonstrated the potential utility of these genes as molecular markers for herbivory by measuring their inductions in grazed individuals of field harvested L. digitata and L. spicata. By unravelling the regulation of some metabolites and genes following grazing pressure in two kelps representative of the two hemispheres, this work contributes to provide a set of herbivore-induced chemical and molecular responses in kelp species, showing similar inducible responses upon specialist herbivores in their respective ecosystems.
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    The Ectocarpus genome and the independent evolution of multicellularity in brown algae
    (2010) Cock, J. Mark; Sterck, Lieven; Rouze, Pierre; Scornet, Delphine; Allen, Andrew E.; Amoutzias, Grigoris; Anthouard, Veronique; Artiguenave, Francois; Aury, Jean-Marc; Badger, Jonathan H.; Beszteri, Bank; Billiau, Kenny; Bonnet, Eric; Bothwell, John H.; Bowler, Chris; Boyen, Catherine; Brownlee, Colin; Carrano, Carl J.; Charrier, Benedicte; Cho, Ga Youn; Coelho, Susana M.; Collen, Jonas; Corre, Erwan; Da Silva, Corinne; Delage, Ludovic; Delaroque, Nicolas; Dittami, Simon M.; Doulbeau, Sylvie; Elias, Marek; Farnham, Garry; Gachon, Claire M. M.; Gschloessl, Bernhard; Heesch, Svenja; Jabbari, Kamel; Jubin, Claire; Kawai, Hiroshi; Kimura, Kei; Kloareg, Bernard; Kuepper, Frithjof C.; Lang, Daniel; Le Bail, Aude; Leblanc, Catherine; Lerouge, Patrice; Lohr, Martin; Lopez, Pascal J.; Martens, Cindy; Maumus, Florian; Michel, Gurvan; Miranda-Saavedra, Diego; Morales, Julia; Moreau, Herve; Motomura, Taizo; Nagasato, Chikako; Napoli, Carolyn A.; Nelson, David R.; Nyvall-Collen, Pi; Peters, Akira F.; Pommier, Cyril; Potin, Philippe; Poulain, Julie; Quesneville, Hadi; Read, Betsy; Rensing, Stefan A.; Ritter, Andres; Rousvoal, Sylvie; Samanta, Manoj; Samson, Gaelle; Schroeder, Declan C.; Segurens, Beatrice; Strittmatter, Martina; Tonon, Thierry; Tregear, James W.; Valentin, Klaus; von Dassow, Peter; Yamagishi, Takahiro; Van de Peer, Yves; Wincker, Patrick
    Brown algae (Phaeophyceae) are complex photosynthetic organisms with a very different evolutionary history to green plants, to which they are only distantly related(1). These seaweeds are the dominant species in rocky coastal ecosystems and they exhibit many interesting adaptations to these, often harsh, environments. Brown algae are also one of only a small number of eukaryotic lineages that have evolved complex multicellularity (Fig. 1). We report the 214 million base pair (Mbp) genome sequence of the filamentous seaweed Ectocarpus siliculosus (Dillwyn) Lyngbye, a model organism for brown algae(2-5), closely related to the kelps(6,7) (Fig. 1). Genome features such as the presence of an extended set of light-harvesting and pigment biosynthesis genes and new metabolic processes such as halide metabolism help explain the ability of this organism to cope with the highly variable tidal environment. The evolution of multicellularity in this lineage is correlated with the presence of a rich array of signal transduction genes. Of particular interest is the presence of a family of receptor kinases, as the independent evolution of related molecules has been linked with the emergence of multicellularity in both the animal and green plant lineages. The Ectocarpus genome sequence represents an important step towards developing this organism as a model species, providing the possibility to combine genomic and genetic(2) approaches to explore these and other(4,5) aspects of brown algal biology further.