ORCID Profile
0000-0001-9995-7387
Current Organisation
CNRS
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Publisher: Springer Science and Business Media LLC
Date: 04-05-2016
DOI: 10.1038/SREP25209
Abstract: Microalgae have emerged as a promising source for biofuel production. Massive oil and starch accumulation in microalgae is possible, but occurs mostly when biomass growth is impaired. The molecular networks underlying the negative correlation between growth and reserve formation are not known. Thus isolation of strains capable of accumulating carbon reserves during optimal growth would be highly desirable. To this end, we screened an insertional mutant library of Chlamydomonas reinhardtii for alterations in oil content. A mutant accumulating five times more oil and twice more starch than wild-type during optimal growth was isolated and named c onstitutive o il a ccumulator 1 ( coa1 ). Growth in photobioreactors under highly controlled conditions revealed that the increase in oil and starch content in coa1 was dependent on light intensity. Genetic analysis and DNA hybridization pointed to a single insertional event responsible for the phenotype. Whole genome re-sequencing identified in coa1 a kb deletion on chromosome 14 containing 41 genes. This study demonstrates that, 1), the generation of algal strains accumulating higher reserve amount without compromising biomass accumulation is feasible 2), light is an important parameter in phenotypic analysis and 3), a chromosomal region (Quantitative Trait Locus) acts as suppressor of carbon reserve accumulation during optimal growth.
Publisher: Oxford University Press (OUP)
Date: 13-06-2016
DOI: 10.1104/PP.16.00718
Publisher: Wiley
Date: 12-05-2017
DOI: 10.1111/NPH.14590
Abstract: Epoxide hydrolases ( EH s) are present in all living organisms. They have been extensively characterized in mammals however, their biological functions in plants have not been demonstrated. Based on in silico analysis, we identified At EH 1 (At3g05600), a putative Arabidopsis thaliana epoxide hydrolase possibly involved in cutin monomer synthesis. We expressed At EH 1 in yeast and studied its localization in vivo . We also analyzed the composition of cutin from A. thaliana lines in which this gene was knocked out. Incubation of recombinant At EH 1 with epoxy fatty acids confirmed its capacity to hydrolyze epoxides of C18 fatty acids into vicinal diols. Transfection of Nicotiana benthamiana leaves with constructs expressing At EH 1 fused to enhanced green fluorescent protein ( EGFP ) indicated that At EH 1 is localized in the cytosol. Analysis of cutin monomers in loss‐of‐function Ateh1‐1 and Ateh1‐2 mutants showed an accumulation of 18‐hydroxy‐9,10‐epoxyoctadecenoic acid and a concomitant decrease in corresponding vicinal diols in leaf and seed cutin. Compared with wild‐type seeds, Ateh1 seeds showed delayed germination under osmotic stress conditions and increased seed coat permeability to tetrazolium red. This work reports a physiological role for a plant EH and identifies AtEH1 as a new member of the complex machinery involved in cutin synthesis.
Publisher: Springer Science and Business Media LLC
Date: 30-11-2014
DOI: 10.1007/S00299-014-1711-7
Abstract: Lipid droplet is the major site of neutral lipid storage in eukaryotic cells, and increasing evidence show its involvement in numerous cellular processes such as lipid homeostasis, signaling, trafficking and inter-organelle communications. Although the biogenesis, structure, and functions of lipid droplets have been well documented for seeds of vascular plants, mammalian adipose tissues, insects and yeasts, relative little is known about lipid droplets in microalgae. Over the past 5 years, the growing interest of microalgae as a platform for biofuel, green chemicals or value-added polyunsaturated fatty acid production has brought algal lipid droplets into spotlight. Studies conducted on the green microalga Chlamydomonas reinhardtii and other model microalgae such as Haematococcus and Nannochloropsis species have led to the identification of proteins associated with lipid droplets, which include putative structural proteins different from plant oleosins and animal perilipins, as well as candidate proteins for lipid biosynthesis, mobilization, trafficking and homeostasis. Biochemical and microscopy studies have also started to shed light on the role of chloroplasts in the biogenesis of lipid droplets in Chlamydomonas.
No related grants have been discovered for Frederic Beisson.