Elevated vitamin E content improves all-trans ß-carotene accumulation and stability in biofortified sorghum.

Micronutrient deficiencies are common in locales where people must rely upon sorghum as their staple diet. Sorghum grain is seriously deficient in provitamin A (ß-carotene) and in the bioavailability of iron and zinc. Biofortification is a process to improve crops for one or more micronutrient deficiencies. We have developed sorghum with increased ß-carotene accumulation that will alleviate vitamin A deficiency among people who rely on sorghum as their dietary staple. However, subsequent ß-carotene instability during storage negatively affects the full utilization of this essential micronutrient. We determined that oxidation is the main factor causing ß-carotene degradation under ambient conditions. We further demonstrated that coexpression of homogentisate geranylgeranyl transferase (HGGT), stacked with carotenoid biosynthesis genes, can mitigate ß-carotene oxidative degradation, resulting in increased ß-carotene accumulation and stability. A kinetic study of ß-carotene degradation showed that the half-life of ß-carotene is extended from less than 4 wk to 10 wk on average with HGGT coexpression.

Rapid detection of proteins in transgenic crops without protein reference standards by targeted proteomic mass spectrometry.

BACKGROUND: Liquid chromatography coupled with tandem mass spectrometry is increasingly used for protein detection for transgenic crops research. Currently this is achieved with protein reference standards which may take a significant time or efforts to obtain and there is a need for rapid protein detection without protein reference standards. RESULTS: A sensitive and specific method was developed to detect target proteins in transgenic maize leaf crude extract at concentrations as low as ∼30 ng mg(-1) dry leaf without the need of reference standards or any sample enrichment. A hybrid Q-TRAP mass spectrometer was used to monitor all potential tryptic peptides of the target proteins in both transgenic and non-transgenic samples. The multiple reaction monitoring-initiated detection and sequencing (MIDAS) approach was used for initial peptide/protein identification via Mascot database search. Further confirmation was achieved by direct comparison between transgenic and non-transgenic samples. Definitive confirmation was provided by running the same experiments of synthetic peptides or protein standards, if available. CONCLUSION: A targeted proteomic mass spectrometry method using MIDAS approach is an ideal methodology for detection of new proteins in early stages of transgenic crop research and development when neither protein reference standards nor antibodies are available. © 2016 Society of Chemical Industry.