Camelina sativa: a promising oilseed for producing biofuels on marginal lands: Field production and characterization of a low-pectin seed mutant
AuthorLohaus, Richard H
AdvisorCushman, John C.
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Camelina sativa L. Crantz (large-seeded false flax) (Camelina) is a promising oilseed crop for production of edible oil, seed meal for animal feed rations, and/or biodiesel feedstock. Because Camelina does not require prime agricultural land, it does not compete with food crops, and requires limited irrigation and nitrogen inputs.In 2015 a five-year field trial of eight named varieties at UNR’s Valley Road facility was completed, with harvested plants evaluated for total dry biomass, seed production, and oil content of cleaned seeds. Columbia, Cheyenne, Calera, and Blaine Creek were ranked as the top four varieties based on performance stability in high seed yield and calculated oil yield. The yields of this study fall within the ranges reported in both irrigated and rainfed locations of the western United States. Improving Camelina for cultivation in Nevada includes developing and identifying mutants with desirable phenotypes (e.g., higher oil content per seed, reduced glucosinolates, reduced seed coat mucilage, triacylglycerol desaturation, and shattering of seed pods). More than 4,700 chemically mutagenized (e.g., EMS, ethyl methane sulfonate) M2 C. sativa lines were generated and have been screened for phenotypes of interest, i.e., oil content as a % of dry weight (DW), reduced glucosinolates, and seed coat mucilage defects. Mucilage is a polysaccharide gum composed of rhamnogalacturonan I (RGI), which can interfere with oil extraction. EMS lines with absent or reduced seed coat mucilage were assayed via a high-throughput colorimetric screen using Ruthenium Red staining. To date 250 M3 mutant lines were screened and four promising lines with reduced mucilage were verified for stability and penetrance in the M4 and M5 generations. The overall rate of mucilage defects in this population is approximately 0.05%. Agronomic data was collected comparing the most promising line, Cs98, with Wild type cv. ‘Celine’ and their F1 cross, Cross 17.1. Cs98 stocks demonstrated their viability through a successful 2016 field trial. A quantitative spectrophotometric mucilage assay validated the seed coat mucilage content compared to wild type “Celine.” Mucilage-defect mutant line Cs98 had smaller seeds and less SCM than WT. Oil derived from Cs98 showed significantly higher macromineral levels (K, Ca, Mg, and P) than WT oil. Transesterification of oil into FAMEs reduced macro mineral content by one-to-two orders of magnitude for both WT and Cs98 FAMEs. Cs98 oil showed significantly lower viscosity at 40 °C than WT oil, perhaps due to lower pectin content. A colorimetric assay of the water washes of the two oils showed that Cs98 had only 57.1% of the mucilage and pectic substances compared to WT. Ongoing research includes characterization of the RGI structure and composition in C. sativa Cs98 mucilage defect lines. Characterization includes backcrossing promising lines to clarify genetic background, and mapping the location of the genetic lesions causing the mucilage defects.