Camelina seed transcriptome: Tool for meal and oil improvement and translational research

Authors: NGUYEN, TAM - University Of Nebraska; COLLINS-SILVA, JILLIAN - University Of Nebraska; MACRANDER, JASON - University Of Nebraska; YANG, WENYU - Danforth Plant Science Center; NAZARENUS, TARA - University Of Nebraska; NAM, JEONG-WAN - Danforth Plant Science Center; JAWORSKI, JAN - Danforth Plant Science Center; LU, CHAOFU - Montana State University; Scheffler, Brian; MOCKAITIS, KEITHANNE - Indiana University; CAHOON, EDGAR - University Of Nebraska

Submitted to: Plant Biotechnology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/19/2013
Publication Date: 4/4/2013
Citation: Nguyen, T., Collins-Silva, J.E., Macrander, J., Yang, W., Nazarenus, T.J., Nam, J., Jaworski, J.G., Lu, C., Scheffler, B.E., Mockaitis, K., Cahoon, E.B. 2013. Camelina seed transcriptome: Tool for meal and oil improvement and translational research. Plant Biotechnology Journal. pp. 1-11.

Interpretive Summary: Fuels derived from renewable agricultural based systems are of national interest for long term fuel stability within the U.S.A. Various plants naturally produce significant levels of biological oils in their seeds. Camelina (Camelina sativa), a Brassicaceae oilseed, is of potential interest as a platform to produce industrial oils. However, the overall oil profile within camelina presently limits its use for larger production operations. For one, camelina has unstable polyunsaturated fatty acids that are bad for biodiesel based systems. In order to alter the oil profile of camelina it is important to isolate and characterize the genes associated with fatty acid production. In this research, cDNAs (representing expressed genes) within seeds were isolated and then sequenced using two different sequencing platforms. The DNA sequence of these cDNAs were compared to those from the model plant Arabidopsis to identify genes know to be related to fatty acid production. To validate these results, two genes were knocked out in camelina using a technology called RNAi which modified fatty acid production as predicted. A database for camelina transcripts (cDNAs) was also generated. These results and data open the door for major experimentation to alter the oil profile of camelina to make it an ideal system to produce biologically produced oils for industrial purposes.

Technical Abstract: Camelina (Camelina sativa), a Brassicaceae oilseed, has received intense interest as a biofuel crop and production platform for industrial oils. Limiting wider production of camelina for these uses is the need to improve seed composition traits such as the quality and content of the protein rich-meal and oil. Vegetable oil derived from camelina seeds, for example, contains high levels of oxidatively unstable polyunsaturated fatty acids that are deleterious for biodiesel. To identify candidate genes for improvement of meal and oil quality, 2,000 Sanger ESTs and ~27,000 454 ESTs were generated from developing camelina seeds. Notably, the average sequence identity between homologs in Arabidopsis and camelina was 93%. These sequences included contigs for the 12S (cruciferins) and 2S (napins) seed storage proteins (SSPs) and nearly all of the known lipid genes, which have been compiled into a publicly accessible-database. To demonstrate the utility of the transcriptome for seed quality modification, seed-specific RNAi lines were generated using this sequence information that are deficient in napins by targeting 2S SSP genes and that have high oleic oil by targeting fatty acid desaturase 2 (FAD2) and fatty acid elongase 1 (FAE1). The high sequence identity between Arabidopsis and camelina genes was also exploited to engineer high oleic oil lines by RNAi with Arabidopsis FAD2 and FAE1 sequences. It is expected that this transcriptomic data will be useful for breeding and engineering of additional traits in camelina seeds for biofuel and other applications and for translating findings from the model Arabidopsis thaliana to an oilseed crop.