title: Transcriptome analysis of Sacha Inchi (Plukenetia volubilis L.) seeds at two developmental stages.
abstract: BACKGROUND
  Sacha Inchi (Plukenetia volubilis L., Euphorbiaceae) is a potential oilseed crop because the seeds of this plant are rich in unsaturated fatty acids (FAs). In particular, the fatty acid composition of its seed oil differs markedly in containing large quantities of α-linolenic acid (18C:3, a kind of ω-3 FAs). However, little is known about the molecular mechanisms responsible for biosynthesis of unsaturated fatty acids in the developing seeds of this species. Transcriptome data are needed to better understand these mechanisms.
  
  
  RESULTS
  In this study, de novo transcriptome assembly and gene expression analysis were performed using Illumina sequencing technology. A total of 52.6 million 90-bp paired-end reads were generated from two libraries constructed at the initial stage and fast oil accumulation stage of seed development. These reads were assembled into 70,392 unigenes; 22,179 unigenes showed a 2-fold or greater expression difference between the two libraries. Using this data we identified unigenes that may be involved in de novo FA and triacylglycerol biosynthesis. In particular, a number of unigenes encoding desaturase for formation of unsaturated fatty acids with high expression levels in the fast oil accumulation stage compared with the initial stage of seed development were identified.
  
  
  CONCLUSIONS
  This study provides the first comprehensive dataset characterizing Sacha Inchi gene expression at the transcriptional level. These data provide the foundation for further studies on molecular mechanisms underlying oil accumulation and PUFA biosynthesis in Sacha Inchi seeds. Our analyses facilitate understanding of the molecular mechanisms responsible for the high unsaturated fatty acids (especially α-linolenic acid) accumulation in Sacha Inchi seeds.
authors.affiliation: Key Laboratory of Tropical Plant Resource Science, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 88 Xuefu Road, Kunming 650223, China.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Wang
authors.forename: Ronghua
authors.initials: R
authors.lastname: Xu
authors.forename: Ruling
authors.initials: R
authors.lastname: Wang
authors.forename: Aizhong
authors.initials: A
authors.lastname: Liu
mesh_terms: D001483:Base Sequence; D019665:Euphorbiaceae / Q000196:embryology / Q000235:genetics*; D015525:Fatty Acids, Omega-3 / Q000096:biosynthesis / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression; D020869:Gene Expression Profiling; D015723:Gene Library; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D059467:Transcriptome; D014280:Triglycerides / Q000096:biosynthesis / Q000378:metabolism; D017962:alpha-Linolenic Acid / Q000235:genetics / Q000378:metabolism
chemical_list: D015525:Fatty Acids, Omega-3; D005231:Fatty Acids, Unsaturated; D014280:Triglycerides; D017962:alpha-Linolenic Acid