Toward increasing erucic acid content in oilseed rape ( Brassica napus L.) through the combination with genes for high oleic acid

Erucic acid (22∶1) is a valuable renewable resource that has several applications in the oleochemical industry. High 22∶1 rapeseed (HEAR) contains around 50% 22∶1. For its technical use it is desirable to increase the 22∶1 content and to decrease the eicosenoic acid (20∶1), PUFA (18∶2+18∶3), and saturated FA (16∶0+18∶0) contents. In the present experiment, HEAR was crossed to high oleic acid rapeseed ( ca . 85% 18∶1) with the hypothesis that a combination of the involved genes should lead to a reduced 18∶1 desaturation and to an increased availability of oleoyl‐CoA, which should result in enhanced 22∶1 synthesis. A NIR spectroscopic calibration for 22∶1 was developed for single seeds, and the calibration was used to select, in a nondestructive manner, F 2 seeds high in 22∶1. Selected F 2 seeds were sown in the field and F 3 seeds were harvested. The results of the FA analysis showed recombinant genotypes with increased total monounsaturated FA (22∶1+20∶1+18∶1) of up to 89% and decreased PUFA (<8%) and saturated FA content (<3.5%). There was no significant difference in 22∶1 content, but a 3 to 5% increase in 20∶1 content was observed in comparison to the HEAR parental cv. Maplus. Results were confirmed following cultivation of selected plant material a second year in the field. The present study revealed that there are other biochemical limitations than the pool of available oleoyl‐CoA that restrict FA elongation to 22∶1 in rapeseed. The generated high 22∶1 plant material with an increased 18∶1 content may be useful in further studies to identify these limitations.