Cyclopropane fatty acid biosynthesis in plants: phylogenetic and biochemical analysis of Litchi Kennedy pathway and acyl editing cycle genes

Authors: Shockey, Jay; Kuhn, David; CHEN, TAO - Chinese Academy Of Agricultural Sciences; Cao, Heping; Freeman, Barbara - Barbie; Mason, Catherine

Submitted to: Plant Cell Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2018
Publication Date: 8/6/2018
Citation: Shockey, J., Kuhn, D., Chen, T., Cao, H., Freeman, B., Mason, C. 2018. Cyclopropane fatty acid biosynthesis in plants: phylogenetic and biochemical analysis of Litchi Kennedy pathway and acyl editing cycle genes. Plant Cell Reports. 37(11):1571-1583. https://doi.org/10.1007/s00299-018-2329-y.
DOI: https://doi.org/10.1007/s00299-018-2329-y

Interpretive Summary: Many agronomically important crops grown in the U.S., and around the world, contain vegetable oils containing unusual fats. These unusual fats may be beneficial, or detrimental, depending on the intended use of the oils or other products produced from the seeds that may contain trace amounts of the oil. Cottonseed and Litchi seeds are examples of plants that produce a type of unusual fatty acid that, if controlled for properly, could add additional value to cottonseed and Litchi producers. Here we have studied several genes from Litchi that may affect how the plant produces the unusual fats. This study is the largest of its kind in that it addresses many parts of the process by which Litchi produces vegetable oil, seeking to learn more about the control of this entire pathway. The findings here may help to design strategies to make better, more marketable cottonseed and Litchi products in the future.

Technical Abstract: Nature contains hundreds of example of plant species that accumulate unusual fatty acids in the seed triacylglycerols (TAG). The underlying mechanisms that control the production of novel TAG species in these plants have not been studied, or are poorly understood at best. One such class of unusual fatty acids contain in-chain cyclopropane or cyclopropene functionalities that confer chemical and physical properties useful in the synthesis of lubricants, cosmetics, dyes, coatings, and other types of valuable industrial feedstocks. These cyclopropyl fatty acids, or CPFAs, are only produced by a small number of plants, primarily in the order Malvidae. Litchi chinensis is one example from this group; its seed oil contains at least 40% CPFAs. Several genes, representing early, middle, and late steps in the fatty acid and TAG biosynthetic pathways have been cloned and characterized here. The tissue-specific and developmental transcript expression profiles and biochemical characteristics of some of the genes tested suggest which enzymes might play a larger role in Litchi seed TAG biosynthesis and accumulation and therefore provide insights into which genes would represent the best targets for either silencing or overexpression, in future metabolic engineering strategies aimed at altering CPFA content.