期刊
PLANT BIOTECHNOLOGY JOURNAL
卷 20, 期 3, 页码 564-576出版社
WILEY
DOI: 10.1111/pbi.13738
关键词
Wheat; carotenoid; lutein; lycopene epsilon-cyclase; beta-carotene; beta-carotene; hydroxylase; provitamin A biofortification; grain; endosperm
资金
- USDA-NIFA [2017-6701326164]
- Howard Hughes Medical Institute
- China Scholarship Council Scholarship
- Henry A. Jastro Research Award
- UC Davis Department of Plant Sciences Graduate Research Fellowship
- Betty and Gordon Moore Foundation
By mutating LCYe and HYD2 homoeologs, the study demonstrated success in increasing beta-carotene content in the endosperm of tetraploid wheat without compromising plant growth and development in other aspects. This provides insights into potential gene editing strategies for provitamin A biofortification in hexaploid wheat.
Grains of tetraploid wheat (Triticum turgidum L.) mainly accumulate the non-provitamin A carotenoid lutein-with low natural variation in provitamin A beta-carotene in wheat accessions necessitating alternative strategies for provitamin A biofortification. Lycopene e-cyclase (LCYe) and beta-carotene hydroxylase (HYD) function in diverting carbons from beta-carotene to lutein biosynthesis and catalyzing the turnover of beta-carotene to xanthophylls, respectively. However, the contribution of LCYe and HYD gene homoeologs to carotenoid metabolism and how they can be manipulated to increase beta-carotene in tetraploid wheat endosperm (flour) is currently unclear. We isolated loss-of-function Targeting Induced Local Lesions in Genomes (TILLING) mutants of LCYe and HYD2 homoeologs and generated higher order mutant combinations of lcye-A, lcye-B, hyd-A2, and hyd-B2. Hyd-A2 hyd-B2, lcye-A hyd-A2 hyd-B2, lcye-B hyd-A2 hyd-B2, and lcye-A lcye-B hyd-A2 hyd-B2 achieved significantly increased beta-carotene in endosperm, with lcye-A hyd-A2 hyd-B2 exhibiting comparable photosynthetic performance and light response to control plants. Comparative analysis of carotenoid profiles suggests that eliminating HYD2 homoeologs is sufficient to prevent beta-carotene conversion to xanthophylls in the endosperm without compromising xanthophyll production in leaves, and that beta-carotene and its derived xanthophylls are likely subject to differential catalysis mechanisms in vegetative tissues and grains. Carotenoid and gene expression analyses also suggest that the very low LCYe-B expression in endosperm is adequate for lutein production in the absence of LCYe-A. These results demonstrate the success of provitamin A biofortification using TILLING mutants while also providing a roadmap for guiding a gene editing-based approach in hexaploid wheat.
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