Product stability and sequestration mechanisms in Solanum tuberosum engineered to biosynthesize high value ketocarotenoids

Mortimer, Cara L., Misawa, Norihiko, Ducreux, Laurence, Campbell, Raymond, Bramley, Peter M., Taylor, Mark, & Fraser, Paul D. (2016) Product stability and sequestration mechanisms in Solanum tuberosum engineered to biosynthesize high value ketocarotenoids. Plant Biotechnology Journal, 14(1), pp. 140-152.

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To produce commercially valuable ketocarotenoids in Solanum tuberosum, the 4, 4′ β-oxygenase (crtW) and 3, 3′ β-hydroxylase (crtZ) genes from Brevundimonas spp. have been expressed in the plant host under constitutive transcriptional control. The CRTW and CRTZ enzymes are capable of modifying endogenous plant carotenoids to form a range of hydroxylated and ketolated derivatives. The host (cv. Désirée) produced significant levels of nonendogenous carotenoid products in all tissues, but at the apparent expense of the economically critical metabolite, starch. Carotenoid levels increased in both wild-type and transgenic tubers following cold storage; however, stability during heat processing varied between compounds. Subcellular fractionation of leaf tissues revealed the presence of ketocarotenoids in thylakoid membranes, but not predominantly in the photosynthetic complexes. A dramatic increase in the carotenoid content of plastoglobuli was determined. These findings were corroborated by microscopic analysis of chloroplasts. In tuber tissues, esterified carotenoids, representing 13% of the total pigment found in wild-type extracts, were sequestered in plastoglobuli. In the transgenic tubers, this proportion increased to 45%, with esterified nonendogenous carotenoids in place of endogenous compounds. Conversely, nonesterified carotenoids in both wild-type and transgenic tuber tissues were associated with amyloplast membranes and starch granules.

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ID Code: 83526
Item Type: Journal Article
Refereed: Yes
Keywords: Ketocarotenoid, carotenoid, Solanum tuberosum, Starch, Sequestration
DOI: 10.1111/pbi.12365
ISSN: 1467-7644
Divisions: Current > Research Centres > Centre for Tropical Crops and Biocommodities
Current > Schools > School of Earth, Environmental & Biological Sciences
Current > Institutes > Institute for Future Environments
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd
Copyright Statement: This is the accepted version of the following article: [full citation], which has been published in final form at
Deposited On: 14 Apr 2015 01:53
Last Modified: 18 May 2016 06:27

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