Response of high leaf-oil Arabidopsis thaliana plant lines to biotic or abiotic stress

Authors: YURCHENKO, OLGA - Former ARS Employee; KIMBERLIN, ATHEN - University Of Missouri; Mehling, Marina; KOO, ABRAHAM - University Of Missouri; CHAPMAN, KENT - University Of North Texas; MULLEN, ROBERT - University Of Guelph; Dyer, John

Submitted to: Plant Signaling and Behavior
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/5/2018
Publication Date: 6/4/2018
Citation: Yurchenko, O., Kimberlin, A., Mehling, M.E., Koo, A.J., Chapman, K., Mullen, R.T., Dyer, J.M. 2018. Response of high leaf-oil Arabidopsis thaliana plant lines to biotic or abiotic stress. Plant Signaling and Behavior. 13(5):e1464361. https://doi.org/10.1080/15592324.2018.1464361.
DOI: https://doi.org/10.1080/15592324.2018.1464361

Interpretive Summary: In recent years there has been significant interest in increasing the energy density of forage and biofuel crops by elevating the oil content in plant leaves and stems. While studies have shown that plants are indeed remarkably amenable to increasing oil content in their vegetative biomass, few studies have been conducted to determine how these engineered plants might respond to environmental challenges encountered in the field. In the current study, scientists at the ARS lab in Maricopa, Arizona, in collaboration with scientists at the University of Missouri, the University of North Texas, and the University of Guelph, showed that Arabidopsis thaliana plant lines engineered for elevated leaf oil content showed similar biochemical and physiological changes in response to short-term (e.g., 3 day) heat exposure in comparison to wild type. However, at extended time periods (e.g., 14 days), the high-leaf-oil plant lines were more susceptible to heat stress and showed earlier plant death. Furthermore, insect feeding studies revealed that the high-oil plant lines were a more nutritious food source for caterpillars, indicating that high-oil plants might be more susceptible to insect predation. Collectively, these experiments highlight the importance of testing high-leaf-oil crops under a variety of biotic and abiotic stress conditions to more carefully evaluate their potential for growth in the field. These studies will be of greatest interest to other scientists and companies interested in developing more energy-dense sources of feed and biofuel crops.

Technical Abstract: Recent studies have shown that it is possible to engineer substantial increases in triacylglycerol (TAG) content in plant vegetative biomass, which offers a novel approach for increasing the energy density of food, feed, and bioenergy crops or for creating a sink for the accumulation of unusual, high-value fatty acids. However, whether or not these changes in lipid metabolism affect plant responses to biotic and/or abiotic stresses is an open question. Here we show that transgenic Arabidopsis thaliana plant lines engineered for elevated leaf oil content, as well as lines engineered for accumulation of unusual conjugated fatty acids in leaf oil, had similar short-term responses to heat stress (e.g., 3 days at 37°C) as wild-type plants, including a reduction in polyunsaturated fatty acid (PUFA)-containing polar lipids and an increase in PUFA-containing neutral lipids. At extended time periods (e.g., 14 days at 37°C), however, plant lines containing accumulated conjugated fatty acids displayed earlier senescence and plant death. Further, no-choice feeding studies demonstrated that plants with the highest leaf oil content generated cabbage looper (Trichoplusia ni) insects with significantly heavier body weights. Taken together, these results suggest that biotic and abiotic responses will be important considerations when developing and deploying high-oil-biomass crops in the field.