Open AccessMolecular cloning and characterization of a KCS gene from Cardamine graeca and its heterologous expression in Brassica oilseeds to engineer high nervonic acid oils for potential medical and industrial use
Author(s) -
Taylor David C.,
Francis Tammy,
Guo Yiming,
Brost Jennifer M.,
Katavic Vesna,
Mietkiewska Elzbieta,
Michael Giblin E.,
Lozinsky Sharla,
Hoffman Travis
Publication year - 2009
Publication title -
plant biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.525
H-Index - 115
eISSN - 1467-7652
pISSN - 1467-7644
DOI - 10.1111/j.1467-7652.2009.00454.x
Subject(s) - biology , erucic acid , brassica carinata , arabidopsis , oleic acid , arabidopsis thaliana , biochemistry , heterologous expression , fatty acid , brassica , botany , gene , mutant , recombinant dna
Summary Nervonic acid 24:1 Δ15 ( cis ‐tetracos‐15‐enoic acid) is a very long‐chain monounsaturated fatty acid and exists in nature as an elongation product of oleic acid. There is an increasing interest in production of high nervonic acid oils for pharmaceutical, nutraceutical and industrial applications. Using a polymerase chain reaction approach, we have isolated a gene from Cardamine graeca L., which encodes a 3‐ketoacyl‐CoA synthase (KCS), the first component of the elongation complex involved in synthesis of nervonic acid. Expression of the Cardamine KCS in yeast resulted in biosynthesis of nervonic acid, which is not normally present in yeast cells. We transformed Arabidopsis and Brassica carinata with the Cardamine KCS under the control of the seed‐specific promoter, napin. The T 3 generations of transgenic Arabidopsis and B. carinata plants expressing the Cardamine KCS showed that seed‐specific expression resulted in relatively large comparative increases in nervonic acid proportions in Arabidopsis seed oil, and 15‐fold increase in nervonic acid proportions in B. carinata seed oil. The highest nervonic acid level in transgenic B. carinata lines reached 44%, with only 6% of residual erucic acid. In contrast, similar transgenic expression of the Cardamine KCS in high erucic B. napus resulted in 30% nervonic acid but with 20% residual erucic acid. Experiments using the Lunaria KCS gene gave results similar to the latter. In both cases, the erucic acid content is too high for human or animal consumption. Thus, the Cardamine KCS: B. carinata high nervonic/highly reduced erucic transgenic seed oils will be the most suitable for testing in pharmaceutical/nutraceutical applications to improve human and animal health.