Emmanuel Geoffriau
Agrocampus Ouest
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Featured researches published by Emmanuel Geoffriau.
Journal of Experimental Botany | 2008
Jérémy Clotault; Didier Peltier; Romain Berruyer; Mathieu Thomas; Mathilde Briard; Emmanuel Geoffriau
Carotenogenesis has been extensively studied in fruits and flower petals. Transcriptional regulation is thought to be the major factor in carotenoid accumulation in these organs. However, little is known about regulation in root organs. The root carotenoid content of carrot germplasm varies widely. The present study was conducted to investigate transcriptional regulation of carotenoid biosynthesis genes in relation to carotenoid accumulation during early carrot root development and up to 3 months after sowing. HPLC carotenoid content analysis and quantitative RT-PCR were compared to quantify the expression of eight genes encoding carotenoid biosynthesis enzymes during the development of white, yellow, orange, and red carrot roots. The genes chosen encode phytoene synthase (PSY1 and PSY2), phytoene desaturase (PDS), zeta-carotene desaturase (ZDS1 and ZDS2), lycopene epsilon-cyclase (LCYE), lycopene beta-cyclase (LCYB1), and zeaxanthin epoxidase (ZEP). All eight genes were expressed in the white cultivar even though it did not contain carotenoids. By contrast with fruit maturation, the expression of carotenogenic genes began during the early stages of development and then progressively increased for most of these genes during root development as the total carotenoid level increased in coloured carrots. The high expression of genes encoding LCYE and ZDS noted in yellow and red cultivars, respectively, might be consistent with the accumulation of lutein and lycopene, respectively. The results showed that the accumulation of total carotenoids during development and the accumulation of major carotenoids in the red and yellow cultivars might partially be explained by the transcriptional level of genes directing the carotenoid biosynthesis pathway.
The Plant Cell | 2014
Jacobo Arango; Matthieu Jourdan; Emmanuel Geoffriau; Peter Beyer; Ralf Welsch
High α-carotene levels present in orange carrots correlate with an insertion in the cytochrome P450 carotene hydroxylase gene CYP97A3/lut5. Overexpression of Arabidopsis lut5 in orange carrots reduces α-carotene and total carotenoid levels as well as the levels of phytoene synthase. This suggests feedback regulation by xanthophyll-derived metabolites acting at levels beyond transcription. The typically intense carotenoid accumulation in cultivated orange-rooted carrots (Daucus carota) is determined by a high protein abundance of the rate-limiting enzyme for carotenoid biosynthesis, phytoene synthase (PSY), as compared with white-rooted cultivars. However, in contrast to other carotenoid accumulating systems, orange carrots are characterized by unusually high levels of α-carotene in addition to β-carotene. We found similarly increased α-carotene levels in leaves of orange carrots compared with white-rooted cultivars. This has also been observed in the Arabidopsis thaliana lut5 mutant carrying a defective carotene hydroxylase CYP97A3 gene. In fact, overexpression of CYP97A3 in orange carrots restored leaf carotenoid patterns almost to those found in white-rooted cultivars and strongly reduced α-carotene levels in the roots. Unexpectedly, this was accompanied by a 30 to 50% reduction in total root carotenoids and correlated with reduced PSY protein levels while PSY expression was unchanged. This suggests a negative feedback emerging from carotenoid metabolites determining PSY protein levels and, thus, total carotenoid flux. Furthermore, we identified a deficient CYP97A3 allele containing a frame-shift insertion in orange carrots. Association mapping analysis using a large carrot population revealed a significant association of this polymorphism with both α-carotene content and the α-/β-carotene ratio and explained a large proportion of the observed variation in carrots.
PLOS ONE | 2015
Matthieu Jourdan; Séverine Gagné; Cécile Dubois-Laurent; Mohamed Maghraoui; Sébastien Huet; Anita Suel; Latifa Hamama; Mathilde Briard; Didier Peltier; Emmanuel Geoffriau
Accumulated in large amounts in carrot, carotenoids are an important product quality attribute and therefore a major breeding trait. However, the knowledge of carotenoid accumulation genetic control in this root vegetable is still limited. In order to identify the genetic variants linked to this character, we performed an association mapping study with a candidate gene approach. We developed an original unstructured population with a broad genetic basis to avoid the pitfall of false positive detection due to population stratification. We genotyped 109 SNPs located in 17 candidate genes – mostly carotenoid biosynthesis genes – on 380 individuals, and tested the association with carotenoid contents and color components. Total carotenoids and β-carotene contents were significantly associated with genes zeaxanthin epoxydase (ZEP), phytoene desaturase (PDS) and carotenoid isomerase (CRTISO) while α-carotene was associated with CRTISO and plastid terminal oxidase (PTOX) genes. Color components were associated most significantly with ZEP. Our results suggest the involvement of the couple PDS/PTOX and ZEP in carotenoid accumulation, as the result of the metabolic and catabolic activities respectively. This study brings new insights in the understanding of the carotenoid pathway in non-photosynthetic organs.
The Plant Cell | 2016
Julia Zinsmeister; David Lalanne; Emmanuel Terrasson; Emilie Chatelain; Céline Vandecasteele; Benoit Ly Vu; Cécile Dubois-Laurent; Emmanuel Geoffriau; Christine Lesignor; Marion Dalmais; Katharina Gutbrod; Peter Dörmann; Karine Gallardo; Abdelhafid Bendahmane; Julia Buitink; Olivier Leprince
ABI5 is a prominent regulator of late seed maturation in legumes, coupling seed vigor with raffinose family oligosaccharide and late embryogenesis abundant protein accumulation and degreening. The preservation of our genetic resources and production of high-quality seeds depends on their ability to remain viable and vigorous during storage. In a quantitative trait locus analysis on seed longevity in Medicago truncatula, we identified the bZIP transcription factor ABSCISIC ACID INSENSITIVE5 (ABI5). Characterization of Mt-abi5 insertion mutant seeds revealed that both the acquisition of longevity and dormancy were severely impaired. Using transcriptomes of developing Mt-abi5 seeds, we created a gene coexpression network and revealed ABI5 as a regulator of gene modules with functions related to raffinose family oligosaccharide (RFO) metabolism, late embryogenesis abundant (LEA) proteins, and photosynthesis-associated nuclear genes (PhANGs). Lower RFO contents in Mt-abi5 seeds were linked to the regulation of SEED IMBIBITION PROTEIN1. Proteomic analysis confirmed that a set of LEA polypeptides was reduced in mature Mt-abi5 seeds, whereas the absence of repression of PhANG in mature Mt-abi5 seeds was accompanied by chlorophyll and carotenoid retention. This resulted in a stress response in Mt-abi5 seeds, evident from an increase in α-tocopherol and upregulation of genes related to programmed cell death and protein folding. Characterization of abi5 mutants in a second legume species, pea (Pisum sativum), confirmed a role for ABI5 in the regulation of longevity, seed degreening, and RFO accumulation, identifying ABI5 as a prominent regulator of late seed maturation in legumes.
Journal of Agricultural and Food Chemistry | 2016
Florent Perrin; Marwa Brahem; Cécile Dubois-Laurent; Sébastien Huet; Matthieu Jourdan; Emmanuel Geoffriau; Didier Peltier; Séverine Gagné
Carotenoids are important secondary metabolites involved in plant growth and nutritional quality of vegetable crops. These pigments are highly accumulated in carrot root, but knowledge about the impact of environmental factors on their accumulation is limited. The purpose of this work was to investigate the impact of environmental variations on carotenoid accumulation in carrot leaves and roots. In this work, carrots were grown during two contrasting periods to maximize bioclimatic differences. In leaves, carotenoid and chlorophyll contents were lower in the less favorable growing conditions, whereas relative contents were well conserved for all genotypes, suggesting a common regulatory mechanism. The down-regulation of all genes under environmental constraints demonstrates that carotenoid accumulation is regulated at the transcriptional level. In roots, the decrease in α-carotene and lutein contents was accompanied by an increase of β-carotene relative content. At the transcriptional level, LCYB and ZEP expression increased, whereas LCYE expression decreased, in the less favorable conditions, suggesting that carotenoid biosynthesis is switched toward the β-branch.
Theoretical and Applied Genetics | 2010
Jérémy Clotault; Emmanuel Geoffriau; Eric Lionneton; Mathilde Briard; Didier Peltier
The Journal of Agricultural Science | 2011
Naouel Jabbes; Emmanuel Geoffriau; Valérie Le Clerc; Boutheina Dridi; Cherif Hannechi
PLOS ONE | 2012
Jérémy Clotault; Didier Peltier; Vanessa Soufflet-Freslon; Mathilde Briard; Emmanuel Geoffriau
Infos-Ctifl | 2012
B. Navez; V. Cottet; F. Villeneuve; M. Jost; Emmanuel Geoffriau; Sébastien Huet
6. International Conference on Managing Quality in Chains | 2015
Brigitte Navez; Valentine Cottet; François Villeneuve; Michel Jost; François Latour; Sébastien Huet; Emmanuel Geoffriau