Clement Pichot, Anis Djari, Joseph Tran, Marion Verdenaud, William Marande, Cécile C. Huneau, David Latrasse, Vivien Sommard, V. Gautier, Judit Szecsi, Sandrine Arribat, Christelle Troadec, Charles Poncet, Mohammed Bendahmane, Catherine Dogimont, Jerome Salse, Moussa Benhamed, Mohamed Zouine, Adnane Boualem, Abdelhafid Bendahmane
Pauline Durand-Smet, Nicolas Chastrette, Axel Guiroy, Alain Richert, Annick Berne-Dedieu, Judit Szécsi, Arezki Boudaoud, Jean-Marie Frachisse, Mohammed Bendahmane, Olivier O. Hamant, Atef Asnacios
Stéphanie Channelière, Stëphane Riviere, Gabriel Scalliet, Judit Szécsi, Frédéric Jullien, Caroline Dolle, Philippe Vergne, Christian Dumas, Mohammed Bendahmane, Philippe Hugueney, J. Mark Cock
The overall objective of our group (PI M. Bendahmane) is to decipher the relationships linking gene regulation and function to plant organ morphogenesis. For these studies we mainly use the petal as a model organ (Szecsi et al., 2014). Petal traits heavily influence flower quality. They play a major role in defining the architecture of the flower thanks to their size, shape, color, scent, number and longevity. During the past few years, we focused on the investigation of the following questions: (1) How cell proliferation and expansion are regulated to attain cell-type and tissue specific values to generate organs (petals) with characteristic shapes and sizes? We use Arabidopsis thaliana to address this task. We identified a group of genes that control some aspects of early and late organ development and morphogenesis. We identified two important pathways involved in mitotic and post-mitotic growth control of petals. We explored the conserved function for one pathway between Arabirospis and Drosophila. (2) ) How important flower characters such as petal number, architecture and scent are defined?
The rose is an ideal model species to address this question. We developed genomic, transcriptomic and biotechnological tools to render the rose an ornamental model species. In parallel, we identified genes involved in the control of petal number and scent production.
The BIGPETAL pathway to control petal morphogenesis: An interplay between jasmonate and auxin
Judit Szecsi , Marion Verdenaud, Jeremy Just, Véronique Boltz.
Our previous work identified a pathway involving two phytohormones to control mitotic and post-mitotic growth during petal morphogenesis. A signal initiated by jasmonates (JA), downstream of organ identity determination, controls the expression of the gene BIGPETAL (BPE; Szecsi et al., 2006) at the post-transcriptional level leading to the production of the alternative splicing variant BPEp (Brioudes et al., 2009). BPEp controls post-mitotic cell expansion by functioning in the JA pathway. BPEp interact synergistically with the AUXIN RESPONSE FACTOR8 (ARF8) to negatively control cell proliferation at early petal development stages while later during petal development BPEp and ARF interact genetically and physically to limit post mitotic cell expansion (Varaud et al., 2011). We aim at discovering the mechanisms underlying jasmonate and auxin signaling and the role of cross talks between those two phytohormones to control mitotic and post-mitotic growth during petal development. More specifically, a first goal is to address the role of JA as signal to control alternative splicing to generate BPEp and to control petal growth and (ii) to unravel the pathway initiated by JA signaling to control petal post-mitotic growth mediated by BPEp.
The TRANSLATIONALLY CONTROLLED TUMOR PROTEIN (tctp) an universal regulator of cell cycle progression during morphogenesis
The link between gene regulation/function and organ size and shape (morphogenesis) is poorly understood in any organism (animals like plants) and remains one of the major issues in developmental biology.
Recently, we used Arabidopsis and Drosophila as models to investigate the biological role of TRANSLATIONALLY CONTROLLED TUMOR PROTEIN (TCTP) and tested the functional conservation between animals and plants. TCTP has been known for a decade to be associated with many human cancers, but its function remains largely uncharacterized. Our study demonstrated that TCTP acts as a positive regulator of mitotic growth by specifically controlling the cell cycle progression at G1/S transition (Brioudes et al., 2010). This study also highlighted that TCTP is part of a conserved growth regulatory pathway shared between plants and animals that regulate cell division. Our work also established Arabidopsis thaliana as an important model to study TCTP function and the gained knowledge may help understanding some health disorders associated with TCTP miss-expression in mammals. We aim at understanding in more details the role of TCTP during mitotic growth. More specifically, we are currently using genetic, molecular and biochemical approaches to address how TCTP controls mitotic growth by acting at cell cycle progression.
Molecular, genomic and transcriptomic approaches to understand flower initiation, development and function in Rosa sp
Olivier Raymond, Jeremy Just, Philippe Vergne, Nicolas Doll, Priscilla Villand, Angèle Noh, Marion Verdenaud, FU Xiaopeng* (*: Huazhong Agriculture University).
Description of the project.
The genus Rosa belongs to the large family of the Rosaceae. Roses are of high symbolic value and have great cultural importance in different societies worldwide. Several characters, involving mainly floral quality, were selected during rose domestication (Bendahmane et al., 2013). These include recurrent flowering, flower morphogenesis (ie. double flower formation), shoot growth and branching, scent biosynthesis and emission, …etc. Some of these characters that can hardly be investigated in Arabidopsis thaliana (or at least in a limited manner), can be studied in the rose. Beside, roses have a relatively small genome size (approximately 560 Mbp) and have a short life cycle for a perennial woody plant (about one year from seeds to flowered plants) (http://www.efor.fr/fiche-rosasp.php).
Rosa sp. Genomic and transcriptomic tools
During the past few years we developed essential tools to make of the rose a model ornamental species. We used the diploid Rosa chinensis cv “Old Blush”, an ancestor of modern roses that contributed several characters (recurrent flowering, scent, etc).
We established a reproducible Agrobacterium-mediated genetic transformation method for “Old Blush” (Vergne et al., 2010). The availability of transformation methods is currently being used for gene functional studies in Rosa sp.
Recently, we used a combination of Illumina and 454 high throughput sequencing technologies to generate information on Rosa sp. transcripts using RNA from various tissues and in response to biotic and abiotic stresses (Dubois et al., 2012; Yan et al., 2014)). A total of 80714 transcript clusters corresponding to at least 20997 individual rose peptides, were identified. A digital expression for each of these clusters, in organs at different development stages and under different stress conditions, was obtained. A Web interface was created that allows data interrogation (https://iant.toulouse.inra.fr/plants/rosa/FATAL/). The database provides useful information on Rosa sp. expressed genes, with thorough annotation and an overview of expression patterns for transcripts with good accuracy, and represents a valuable prerequisite to the sequencing of the rose genome.
At ENS-Lyon, we have now gathered a collection of more than 20 rose species and 30 cultivars representing the botanical sections and horticultural groups, respectively, that have been involved in rose domestication.
The tools we developed are instrumental to address flower morphogenesis in Rosa sp (see review by Bendahmane et al., 2013). We mainly focus on flower initiation (Dubois et al., 2011), floral architecture, especially on the genetic control of petal shape and number, scent biosynthesis and emission (Scalliet et al., 2002; 2006; 2008; Channelière et al., 2002)) and meiosis (collaboration with M. Le Bris, IMBE, Aix-Marseille University, Marseille, France).
Rose flower initiation and double flowers formation
Currently, we use a combination of candidate gene and transcriptomic approaches to identify the molecular mechanisms that control flower initiation, development and petal number per flower in Rosa sp.
We established a framework of genes involved in flower initiation in Rosa using Affymetrix microarrays (Dubois et al., 2011) and candidate gene approaches.
While wild roses all have five petals, most cultivated roses have “double flowers” ranging from 10 petals to as many as 200. In roses, the "double flower" phenotype is associated with a dominant mutation, in the yet unknown DF (DOUBLE FLOWER) locus, which leads to a boundary shift of the rose AGAMOUS (RhAG) expression toward the center of the flower (Dubois et al., 2010). We further showed that a restriction of RhAG expression domain is the basis for selection of double flowers and that it was selected independently in the two major regions for rose domestication, China and the peri-Mediterranean areas (Dubois et al., 2010). To validate the function of selected genes we are using our rose genetic transformation protocol.
Rose scent biosynthesis and emission
Rose fragrance is made of hundreds of volatile compounds. The goal of the project is to explore the functional genomics of scent compounds biosynthesis in roses.
First we identified an orcinol O-methyltransferases (OOMT) involved in the biosynthesis of dimethoxytoluene (a volatile compound responsible for the "tea scent" of modern roses) and deciphered the evolutionary mechanism responsible for the emergence of tea scent in wild Chinese roses (Scalliet et al., FEBS Let 2002 ; Scalliet et al., PNAS 2008).
In the past few years we investigated the molecular basis of the biosynthesis of monoterpenes and 2-phenylethanol, two major scent compounds of the “typical rose scent”. So far in plants, a unique biosynthetic pathway of monoterpenes had been described, with the involvement enzymes belonging to the terpene synthase family. We addressed how monoterpenes are synthetized in roses and why some roses are scentless. We demonstrated that in roses, monoterpene biosynthesis is very original because it does not rely on terpene synthases but on a particular enzyme called a nudix hydrolase, RhNUDX1. Nudix hydrolases are found in animals, plants and bacteria but had never been associated with scent biosynthesis. Our data unravel the missing link between GPP (monoterpenes precursor) and Geraniol biosynthesis. We demonstrated that in rose, RhNUDX1 is involved in scent biosynthesis in petals through dephosphorylation of the precursors of scent molecules GPP. This work was recently published in Science (Magnard et al., 2015).
Currently, we are using genetic and transcriptomic approaches to investigate the pathways involved in major scent compounds in rose petals. This part of the work is done in collaboration with Sylvie Baudino, BVpam laboratory, St Etienne University, France.
Team members BENDAHMANE Mohammed (DR2, INRA)
VERGNE Philippe (IR1 INRAE)
SZECSI Judit (IR1 INRAE)
RAYMOND Olivier (MdC Lyon1)
JUST Jeremy (IR2 CNRS)
BOLTZ Véronique (TR INRAE)
VILLAND Priscilla (ATP2, INRAE)
BARDOUX Claudia (ATP1, INRAE)
DOLL Nicolas (AGPR, ENS de Lyon)
XU Wenqi (PhD, ENS de Lyon)
NOH Angèle Yuo-Myoung (PhD, CIFRE)
POUPARDIN Lucie (PhD, INRAE-Inria-Co-direction with MOSAIC team)
PONCET Adrien (IE, CDD-INRAE)
BELLOT Clement (IE, CDD-INRAE)
Anciens Membres
FRANÇOIS Léa (PhD, ENS de Lyon)
PONTIER Garance (PhD, ENS de Lyon)
THOMAS Jason (PhD. Co-direction, University of Minnesota Twin)
TALARON Hinda (IE CDD INRA)
VERDENAUD Marion (IE CDD CNRS)
BETSCH Léo (PhD, University Lyon1)
SAVARIN Julie (PhD, ENS de Lyon)
XIAOPENG FU (Post-doc-France-China Cooperation FFSCA)
GOVETTO Benjamin (PhD. Co-direction Univ Marseille)
THOMAS Aurélie (IE, CDD-ANR)
HARAGHI Aimen (PhD. Co-direction –IPS2- Univ Orsay
MARTEAUX Benjamin (IE, CDD-ANR)
BROUDES Florian (PhD, 2010)
WIPERMANN Barbara (PhD, 2013)
VIALETTE Aurélie (Post-doc)
ROCCIA Aymeric (PhD, 2013)
LEROUX Julie (IE CDD ANR)
GIRIN Thomas (Post-doc)
YANG Shu-Hua (Post-doc)