title: Comparative transcriptome and metabolite analysis of oil palm and date palm mesocarp that differ dramatically in carbon partitioning.
abstract: Oil palm can accumulate up to 90% oil in its mesocarp, the highest level observed in the plant kingdom. In contrast, the closely related date palm accumulates almost exclusively sugars. To gain insight into the mechanisms that lead to such an extreme difference in carbon partitioning, the transcriptome and metabolite content of oil palm and date palm were compared during mesocarp development. Compared with date palm, the high oil content in oil palm was associated with much higher transcript levels for all fatty acid synthesis enzymes, specific plastid transporters, and key enzymes of plastidial carbon metabolism, including phosphofructokinase, pyruvate kinase, and pyruvate dehydrogenase. Transcripts representing an ortholog of the WRI1 transcription factor were 57-fold higher in oil palm relative to date palm and displayed a temporal pattern similar to its target genes. Unexpectedly, despite more than a 100-fold difference in flux to lipids, most enzymes of triacylglycerol assembly were expressed at similar levels in oil palm and date palm. Similarly, transcript levels for all but one cytosolic enzyme of glycolysis were comparable in both species. Together, these data point to synthesis of fatty acids and supply of pyruvate in the plastid, rather than acyl assembly into triacylglycerol, as a major control over the storage of oil in the mesocarp of oil palm. In addition to greatly increasing molecular resources devoted to oil palm and date palm, the combination of temporal and comparative studies illustrates how deep sequencing can provide insights into gene expression patterns of two species that lack genome sequence information.
authors.affiliation: Université de Bordeaux Ségalen, Laboratoire de Biogenèse Membranaire, Bordeaux, France.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Bourgis
authors.forename: Aruna
authors.initials: A
authors.lastname: Kilaru
authors.forename: Xia
authors.initials: X
authors.lastname: Cao
authors.forename: Georges-Frank
authors.initials: GF
authors.lastname: Ngando-Ebongue
authors.forename: Noureddine
authors.initials: N
authors.lastname: Drira
authors.forename: John B
authors.initials: JB
authors.lastname: Ohlrogge
authors.forename: Vincent
authors.initials: V
authors.lastname: Arondel
mesh_terms: D028023:Arecaceae / Q000235:genetics* / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D002244:Carbon / Q000378:metabolism; D020224:Expressed Sequence Tags; D005227:Fatty Acids / Q000378:metabolism; D005638:Fruit / Q000378:metabolism; D020869:Gene Expression Profiling; D017343:Genes, Plant; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D000073878:Palm Oil; D010802:Phylogeny; D018515:Plant Leaves / Q000378:metabolism; D010938:Plant Oils / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism; D043324:beta-Fructofuranosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D010938:Plant Oils; D010940:Plant Proteins; D014157:Transcription Factors; D014280:Triglycerides; D000073878:Palm Oil; D002244:Carbon; D005964:Glucosyltransferases; C022699:sucrose synthase; D043324:beta-Fructofuranosidase