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Title: De novo transcriptome sequencing in Bixa orellana to identify genes involved in methylerythritol phosphate, carotenoid and bixin biosynthesis

Bixin or annatto is a commercially important natural orange-red pigment derived from lycopene that is produced and stored in seeds of Bixa orellana L. An enzymatic pathway for bixin biosynthesis was inferred from homology of putative proteins encoded by differentially expressed seed cDNAs. Some activities were later validated in a heterologous system. Nevertheless, much of the pathway remains to be clarified. For example, it is essential to identify the methylerythritol phosphate (MEP) and carotenoid pathways genes. In order to investigate the MEP, carotenoid, and bixin pathways genes, total RNA from young leaves and two different developmental stages of seeds from B. orellana were used for the construction of indexed mRNA libraries, sequenced on the Illumina HiSeq 2500 platform and assembled de novo using Velvet, CLC Genomics Workbench and CAP3 software. A total of 52,549 contigs were obtained with average length of 1,924 bp. Two phylogenetic analyses of inferred proteins, in one case encoded by thirteen general, single-copy cDNAs, in the other from carotenoid and MEP cDNAs, indicated that B. orellana is closely related to sister Malvales species cacao and cotton. Using homology, we identified 7 and 14 core gene products from the MEP and carotenoid pathways, respectively. Surprisingly, previously definedmore » bixin pathway cDNAs were not present in our transcriptome. Here we propose a new set of gene products involved in bixin pathway. In conclusion, the identification and qRT-PCR quantification of cDNAs involved in annatto production suggest a hypothetical model for bixin biosynthesis that involve coordinated activation of some MEP, carotenoid and bixin pathway genes. These findings provide a better understanding of the mechanisms regulating these pathways and will facilitate the genetic improvement of B. orellana.« less
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [2] ;  [1]
  1. Centro de Investigacion Cientifica de Yucatan, Yucatan (Mexico)
  2. Univ. of California, Davis, CA (United States)
Publication Date:
OSTI Identifier:
1239151
Grant/Contract Number:
SC0007183
Type:
Accepted Manuscript
Journal Name:
BMC Genomics
Additional Journal Information:
Journal Volume: 16; Journal Issue: 1; Journal ID: ISSN 1471-2164
Publisher:
Springer
Research Org:
Univ. of California, Davis, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
annatto; Bixa orellana; lipstick tree; transcriptome; Bixin synthesis; carotenoids