Research teams

Cell Differentiation and Polarity

DIPOL 9 members 64 publications

Plant engineering and synthetic biology
DIPOL group has developped several research projects in translational research to develop new oilseed crop model in the context of more sustainable agriculture.
The objective is to use a wide range of approaches to modify and improve different plant traits useful in broadening end-uses ranging from nutrition and health to agro-ecology. Arabidopsis research in DIPOL group identified several lipids (fatty acids and sphingolipids) providing results of potential interest for improving oil yield and quality. The oleaginous crop Camelina sativa, a Brassicae specie that is easy to transform and to extract oil from was used to evaluate the potentials of Arabidopsis discoveries.
Camelina flowers
Translational projects include the modification of lipid accumulation in oil, the shortening of flowering time and the development of "sentinel" plant for environmental monitoring.

Design new Camelina oil profiles : from engineered plants to end-users. Desaturation of oleic acid by the FAD2 and FAD3 desaturase allows the synthesis of the omega6 linoleic acid and omega3 linolenic acid. Selective, targeted mutagenesis of the three delta-12-desaturase (FAD2) genes was achieved in the translational model Camelina sativa by CRISPR-Cas9 gene editing providing a large diversity of Camelina lines with various lipid profiles, ranging from 10% to 62% oleic acid accumulation in the oil (Morineau et al. 2017). The impact of reduction of polyunsaturated fatty acids on plant development and response to stress are currently investigated.
Synthetic biology approaches are also carried out to channel specific fatty acids into oil. It involves innovative strategies combining multiplex CRISPR chassis improvement and synthetic enzymatic assembly. New combination of enzymes and mutants are now tested to obtain a wide range of oil profile. The main objective is to produce new camelina plants with relevant FA profiles and tailored lipids.

Developping new traits require field validation to assess their pertinence in real agronomic conditions.

Edited camelina plants were evaluated in 2018 and 2019 in field trials for the first time in Europe (Faure and Napier 2018). Oil quality could have some important impact on human and animal health. The potential benefits of plant sphingolipids accumulated in seeds for animal nutrition and health was evaluated for the first time in the AgroParisTech funded project NUTRICAM. Camelina seeds with highly contrasted sphingolipid profiles were used to evaluate for the first time their effects on mice metabolic syndrome and gut inflammation (Hermier et al. 2020).

Design early flowering Camelina. Camelina's short life cycle opens particularly interesting possibilities for double cropping that would have positive agro-ecological benefits: decreasing the duration of land being left bare will reduce soil erosion; integration of camelina in European rotation schemes will also increase crop diversity. Combination of traditional breeding with natural accession and multiplexed mutagenesis of flowering repressor genes by CRISPR identified several new camelina early flowering lines that will have to be assess in various cropping conditions.

Develop abiotic and biotic sensors environmental monitoring. The use of OPIOM patented technology allowed remote detection of fluorescence even in bright light (Querard et al. 2017, Zhang et al. 2019). This technology could now be used to monitor abiotic and biotic environmental changes and to provide real time quantitative and specific evaluation of the physiological state of cultures.


Cell identity, reprogrammation, regeneration
The remarkable capacity of plants to regenerate new individuals relies largely on their ability to specify new stem cells niche to establish de novo apical meristems. The initiation of a shoot meristem (SM) is a key step in many methods for regeneration of true-to-type adult plants from in vitro cultured tissues. In this context, converging evidence suggests that SM initiation does not always require dedifferentiation but may also occur through trans-differentiation, i.e. the direct transition of cell types in others. For example, our lab showed recently that Arabidopsis thaliana lateral root primordia (LRPs) can be converted into a shoot meristem. We recently discovered that the switch of organ identity relied on the incipient root apical stem cell niche and the surrounding cell layers that are recruited to form the novel SM through active and coordinated cell divisions. Cell fate transitions appears to be the driving force of regeneration.

1) polarity and (re)-organization of cell identity. The positional information that specify cell identities seems to be governed by the precise and dynamic distribution of auxin efflux carriers proteins (like PIN1 protein) that controls the directional auxin fluxes all along the conversion process. The dynamic evolution of the morphogenetic auxin gradients could instruct qualitatively different cellular state changes that progressively re-specify cells identities to orchestrate the position of the new shoot stem cell niche.

2) Meristem conversion is a unique system to investigate morphogenesis and can be exploited to answer a number of fundamental questions addressing the cellular and molecular mechanisms of cell fate determination and cellular reprogramming, or the discovery of new regulators capable of conferring regenerative potential to recalcitrant plant species .
Tools: 3DWholemount ISH, immune...The dynamic nature of the conversion process necessitates the development of modern approaches as ad’hoc 3D+time imaging techniques, advances technology in single-cell profiling, Cell specific ablation by laser nanodissection techniques, design of microfluidic devices to study in vivo meristem conversion.


Regulation of localized lipid metabolism in the endoplasmic reticulum and stress tolerance
In eukaryotic cells, the endoplasmic reticulum (ER) is the site of synthesis, folding and maturation of the majority of secreted proteins, whether soluble or membrane-bound; it accounts for nearly one-third of the cell's proteins. It is also at the level of this organelle that the synthesis and modification of several families of lipids take place, such as very long-chain fatty acids, phospholipids, sphingolipids or the triglycerids that make up oils. In plant cells, the coordination of these two types of metabolism (lipid and protein) ensures the homeostasis of the ER. In this context, we are interested in the impact of biotic and abiotic stresses on the regulation of ER protein and lipid biosynthesis and are seeking to understand them using the Arabidopsis thaliana model. Conversely, we use mutants with a loss of protein or lipid homeostasis to understand the role of these metabolic changes in stress tolerance.
 
Cell Differentiation and Polarity

Leader:

Jean-Denis Faure
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