title: Regulatory mechanisms underlying oil palm fruit mesocarp maturation, ripening, and functional specialization in lipid and carotenoid metabolism.
abstract: Fruit provide essential nutrients and vitamins for the human diet. Not only is the lipid-rich fleshy mesocarp tissue of the oil palm (Elaeis guineensis) fruit the main source of edible oil for the world, but it is also the richest dietary source of provitamin A. This study examines the transcriptional basis of these two outstanding metabolic characters in the oil palm mesocarp. Morphological, cellular, biochemical, and hormonal features defined key phases of mesocarp development. A 454 pyrosequencing-derived transcriptome was then assembled for the developmental phases preceding and during maturation and ripening, when high rates of lipid and carotenoid biosynthesis occur. A total of 2,629 contigs with differential representation revealed coordination of metabolic and regulatory components. Further analysis focused on the fatty acid and triacylglycerol assembly pathways and during carotenogenesis. Notably, a contig similar to the Arabidopsis (Arabidopsis thaliana) seed oil transcription factor WRINKLED1 was identified with a transcript profile coordinated with those of several fatty acid biosynthetic genes and the high rates of lipid accumulation, suggesting some common regulatory features between seeds and fruits. We also focused on transcriptional regulatory networks of the fruit, in particular those related to ethylene transcriptional and GLOBOSA/PISTILLATA-like proteins in the mesocarp and a central role for ethylene-coordinated transcriptional regulation of type VII ethylene response factors during ripening. Our results suggest that divergence has occurred in the regulatory components in this monocot fruit compared with those identified in the dicot tomato (Solanum lycopersicum) fleshy fruit model.
authors.affiliation: Institut de Recherche pour le Développement, UMR Diversité et Adaptation et Développement des Plantes, 34394 Montpellier cedex 5, France. timothy.tranbarger@ird.fr
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Tranbarger
authors.forename: Stéphane
authors.initials: S
authors.lastname: Dussert
authors.forename: Thierry
authors.initials: T
authors.lastname: Joët
authors.forename: Xavier
authors.initials: X
authors.lastname: Argout
authors.forename: Marilyne
authors.initials: M
authors.lastname: Summo
authors.forename: Antony
authors.initials: A
authors.lastname: Champion
authors.forename: David
authors.initials: D
authors.lastname: Cros
authors.forename: Alphonse
authors.initials: A
authors.lastname: Omore
authors.forename: Bruno
authors.initials: B
authors.lastname: Nouy
authors.forename: Fabienne
authors.initials: F
authors.lastname: Morcillo
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D028023:Arecaceae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D055162:Biocatalysis; D053898:Biosynthetic Pathways; D002338:Carotenoids / Q000378:metabolism*; D020451:Contig Mapping; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D005227:Fatty Acids / Q000096:biosynthesis; D005638:Fruit / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D050356:Lipid Metabolism; D026161:MADS Domain Proteins / Q000235:genetics; D008954:Models, Biological; D058977:Molecular Sequence Annotation; D000073878:Palm Oil; D010938:Plant Oils / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018087:Plastids / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013696:Temperature; D014158:Transcription, Genetic; D014280:Triglycerides / Q000096:biosynthesis
chemical_list: D005030:Ethylenes; D005227:Fatty Acids; D026161:MADS Domain Proteins; D010938:Plant Oils; D010940:Plant Proteins; D012333:RNA, Messenger; D014280:Triglycerides; D002338:Carotenoids; D000073878:Palm Oil; D000040:Abscisic Acid; C036216:ethylene