Genetic variation of palmitate and oil content in a winter oilseed rape doubled haploid population segregating for oleate content

Increasing the oil content and reducing the content of saturated fatty acids in seed oil are important breeding goals for rapeseed (Brassica napus L.). The objective of the study was to investigate the influence of a major change in oleate content on the palmitate and oil content. An oilseed rape doubled haploid (DH) population (n = 60) segregating for one major gene mutation, that increases the oleate content in the seed oil by 11%, was used in a field experiment in five environments. Subdividing the DH lines into normal and high oleate classes showed that the mutation caused a significant reduction in the saturated fatty acids palmitate and stearate and of the ratio of total C16 to total C18 fatty acids(C16/C18). The high oleate class had a significantly increased oil content and an identical protein content, compared with the normal oleate class. Both oleate classes showed a significant negative correlation for oleate and palmitate and a significant positive correlation for oleate and oil content, and oil content was negatively correlated with palmitate. The results show that the high oleate mutation has a pleiotropic effect on palmitate and oil content. The beta-ketoacyl-acyl carrier protein (ACP) synthase II (KAS II) activity reflected by the C16/CI8 ratio has been used to explain this effect. Results indicated that palmitate content can be reduced either by recurrent selection for increased oleate content or continued selection for high oil content.