Evaluating the genetic and phenotypic responses of Camelina sativa to heat stress

Abstract

Camelina sativa (L.) Crantz is a low-input oilseed crop with a unique fatty acid profile in its seed oil. Camelina oil can be used in biodiesels, jet fuels, and industrial lubricants. Improving the abiotic stress tolerance of camelina is a crucial step for increasing agronomic viability. Climate change is threatening production of camelina with rising global temperatures and shorter growing seasons. Elucidating the phenotypic and genetic responses to high temperatures is essential for successful breeding of heat tolerant camelina varieties. Three experiments were conducted to understand these responses. Two genotypes, Suneson (MT5) and Pryzeth (MT102) were exposed to a transient 14-day heat stress during the reproductive stage and evaluated for agronomic and seed quality traits along the main stem. Next, a mapping population consisting of 257 recombinant inbred lines (RILs) were grown under the same temperature regimes for 14 days beginning at the onset of the reproductive stage. Finally, reproductive tissues undergoing heat stress from two genotypes with contrasting heat responses, RIL23 and RIL167, were examined with RNA sequencing, and the phenotypes along the main stem were compared. From the phenotype evaluation, both MT5 and MT102 were significantly impacted by heat. Both genotypes experienced reductions in seed and pod size, seed weight, and total oil contents. As reported in other oilseed crops, camelina is negatively affected by heat, characterized primarily by lower yield and reduced oil content. The QTL analysis identified several key gene regions with co-located traits on chromosomes 8, 10, and 12. This demonstrates the ability to identify heat-responsive gene regions via phenotyping along the main stem. The transcriptomes of RILs 23 and 167 contrasted in both sampled tissue types, with RIL23 appearing more responsive to heat. Phenotypic analysis of these genotypes confirmed the transcriptional differences, as RIL23 was more resistant for several traits associated with fertility. These studies provide resources and protocols for future studies that may assist in improving the heat-tolerance of camelina.