Engineered Cleistogamy in Camelina sativa for bioconfinement

Abstract

Camelina sativa is a self-pollinating and facultative outcrossing oilseed crop. Genetic engineering has been used to improve camelina yield potential for altered fatty acid composition, modified protein profiles, improved seed and oil yield, and enhanced drought resistance. The deployment of transgenic camelina in the field posits high risks related to the introgression of transgenes into non-transgenic camelina and wild relatives. Thus, effective bioconfinement strategies need to be developed to prevent pollen-mediated gene flow (PMGF) from transgenic camelina. In the present study, we overexpressed the cleistogamy (i.e. floral petal non-openness)-inducing PpJAZ1 gene from peach in transgenic camelina. Transgenic camelina overexpressing PpJAZ1 showed three levels of cleistogamy, affected pollen germination rates after anthesis but not during anthesis, and caused a minor silicle abortion only on the main branches. We also conducted field trials to examine the effects of the overexpressed PpJAZ1 on PMGF in the field, and found that the overexpressed PpJAZ1 dramatically inhibited PMGF from transgenic camelina to non-transgenic camelina under the field conditions. Thus, the engineered cleistogamy using the overexpressed PpJAZ1 is a highly effective bioconfinement strategy to limit PMGF from transgenic camelina, and could be used for bioconfinement in other dicot species.

Acknowledgements

This project was supported by Biotechnology Risk Assessment Grant Program competitive grant no. 2016-33522-25627 from the U.S. Department of Agriculture, the Hatch project 02685 from the U.S. Department of Agriculture National Institute of Food and Agriculture, and the startup funding to the Liu laboratory from North Carolina State University. We thank Dr. Heike Sederoff for the non-transgenic camelina cv. Calena seeds.

Author contributions

WL conceived and designed the project. DH, LG, and JA conducted the experiments and collected the data. DH, LG, and YW performed camelina transformation. DH, JM, FZ, HL, JM, and WL performed the field trials. DH, HD, and WL analyzed the data and wrote the manuscript. SS and JS provided the PpJAZ1 gene. All authors helped with manuscript writing, and read and approved the final manuscript.

Data availability

All the data supporting the findings of the present study are available within the paper and its supplementary data.

Conflicts of interest statement

None declared.

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