Camelina biotypes had different responses to freezing stress, which was mainly inherited by additive gene effects and can be reliably used in breeding programs and for a better understanding of freezing tolerance mechanisms in camelina plants. Camelina [Camelina sativa (L.) Crantz] is a frost-tolerant oilseed plant that is cultivated as an autumn crop in semi-arid regions. However, camelina establishment in these areas is limited by low temperatures in winter that results in decreased seed yield. In the present study, genetic basis of freezing tolerance (FT) in spring and winter biotypes of camelina was analyzed at seedling stage using a diallel cross experiment. The parents consisted of two winter doubled haploid (DH) lines with high (DH34 and DH31), two spring lines with medium (DH19 and DH26), and two spring lines with low FT (DH08 and DH91). For this purpose, the parents along with F1 entries were subjected to freezing stress and survival percentage, electrolyte leakage, and lethal temperature for 50% mortality (LT50) of the lines were measured. Results showed that although both additive and non-additive effects of the genes determine the FT, further analyses indicated that it was mainly controlled by the additive effects. Therefore, selection-based methods may be more efficient for improving FT in camelina genotypes. The results of specific combining ability (SCA) and heterosis analysis among various DH lines suggested that more tolerant cultivars of camelina could be developed by targeted crossings. When a tolerant winter line and a susceptible spring line were crossed, their progenies showed a higher FT compared with the progenies of a cross between two susceptible spring lines indicating FT is controlled by additive effects of the genes in camelina plants. These findings provided new insight into the genetic basis of freezing-related traits in camelina and could be used for more sophisticated breeding programs.
Keywords: Camelina; Combining ability; Freezing tolerance; Heritability; Oilseed crop.