Location: Weed and Insect Biology Research
Project Number: 3060-21220-033-029-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Aug 1, 2025
End Date: Jul 31, 2026
Objective:
The overall goal of the proposal is to identify novel oilseed germplasm with sustainable low carbon intensity as a source for alternative aviation biofuels. Because yield is a significant factor contributing to low carbon intensity, we will focus on identifying germplasm from a novel oilseed crop (camelina) that has been reported to perform well on marginal land (e.g., saline soils) or under environmental stress (e.i., heat stress during flowering) and produce the best final oilseed yield. The specific objectives relevant to the work ARS investigators will accomplish includes: 1.) phenotyping an existing population of 255 Recombinant Inbred Lines (RILs) of camelina for abiotic stress tolerance (heat and salinity) under controlled or field environments and identify the QTLs and potential genes associated with stress tolerance and seed yield; 2.) increase the seed quantity of the USDA collection of spring and winter biotypes of camelina (210 accessions) under greenhouse conditions and phenotype and genotype the accessions under greenhouse and field conditions to identify stress tolerant germplasm; and 3.) participate in efforts to bridge gaps between science-based results and breeding programs for developing camelina as a sustainable low carbon intensity oilseed crop for alternative aviation biofuels.
Approach:
To evaluate the impact of heat (during the flowering period) on camelina seed yield, we will phenotype our F7 generation of RILs developed from crossing a spring (CO46) and winter (Joelle) biotype. Seed from each RIL will be grown in a greenhouse. At the 2-week seeding stage plants will be transferred to a growth chamber and vernalized six weeks (5 C) to induce uniform flowering. After vernalization, plants will be maintained at 22 C/15 C under 16:8 hour light:dark conditions. Once 50% of the plants reach the flower development stage, plants will either continue growth and development at 22 C/15 C (control) or be exposed to 32 C/25 C (heat stress) for 4 weeks and then transferred to a greenhouse for final maturation and phenotyping (seed yield). A set of markers from the F7 RILs used to develop a linkage map to the 20 camelina chromosomes will be used to identify QTLs and potential candidate genes associated with the impact of heat stress on final seed yield.
To identify germplasm suitable for marginal land (saline soils), we will first phenotype the parents (CO46 and Joelle) of the RILs for salinity tolerance. A total of 50 seeds, replicated three times will be germinated in Petri dishes saturated with NaCl, CaCl, and Na2SO4 solution at 0, 2, 4, 8, and 16¿ dS m-1 in an incubator at constant 20 C. Fully germinated seeds will be counted and removed daily for 7¿ days, followed by every other day for a total of 21¿ days. Final germination percent, corrected germination rate index, and germination velocity will be calculated. If the parents have differential tolerance to salinity, RNAseq analysis will be used to identify genes showing differential expression. Phenotyping of the F7 RILs, using methods described for the parents, will be used to identify QTLs linked to the trait and potential candidate genes associated with salinity tolerance. Salt and concentration will be selected according to differences observed between seed germination of CO46 and Joelle. A subset of RILs showing segregation for salinity tolerance will also be evaluated under field conditions.
To phenotype our diversity panel of 210 camelina accessions for salinity tolerance, we will first increase seed quantities in the collection under greenhouse conditions. A vernalization treatment, as previously described, will be used to initiate flowering in winter biotypes. Leaf tissue from three replicate plants/accessions will be collected to extract DNA and conduct genotyping-by-sequencing (GBS) and identify single nucleotide polymorphism (SNP) markers, construct a linkage map, and identify QTLs using inhouse and previously published approaches. Protocols described above for phenotyping RILs will be used to identify QTLs and potential candidate genes associated with salinity tolerance. We also plan to bulk 10 seeds from each accession and plant as a single strip plot at locations with high salinity soils. Leaf tissue from plants that show tolerance to salinity (grow and produce seed yield) under field conditions will also be genotyped and compared back to the originally genotyped accessions to identify camelina lines in the collection that carry salinity tolerance traits.