A fast and simplified method to estimate bioaccessibility of carotenoids from plant tissues

Open avenues for carotenoid biofortification of plant tissues

“…The proliferation of plastoglobules and other storage structures in crtB-triggered artificial chromoplasts also stimulated accumulation of other isoprenoid compounds such as tocopherols (vitamin E) and phylloquinone (vitamin K) ( Morelli et al., 2022 ). This strategy works to biofortify leaves and other green tissues with carotenoids and lipophilic isoprenoid vitamins in multiple plant systems, including edible crops such as lettuce and zucchini ( Llorente et al., 2020 ; Morelli and Rodriguez-Concepcion, 2021 ; Torres-Montilla and Rodriguez-Concepcion, 2021 ; Houhou et al., 2022 ). The loss of photosynthetic activity associated with the transition from chloroplasts to chromoplasts, however, makes this approach suitable for plant biofortification only when photosynthesis is dispensable (e.g., immediately before harvest).…”

“…Assessment of bioavailability requires in vivo assays, but bioaccessibility can be determined using in vitro methods that simulate the chemical environment and reactions that occur in the human gastrointestinal tract during digestion. Recent efforts to simplify bioaccessibility determinations and adapt the protocols to the expertise and equipment typically available in molecular biology laboratories like those involved in carotenoid biotechnology are expected to help make bioaccessibility data a routine part of biofortification reports ( Morelli and Rodriguez-Concepcion, 2021 ).…”

“…Nonetheless, some of the strategies described above show that it is possible to improve production, storage (i.e., stability), and bioaccessibility. For example, the bioaccessibility of phytoene was higher when it was produced in the cytosol rather than the chloroplasts of leaf cells ( Andersen et al., 2021 ), and β-carotene was more bioaccessible when acquired from crtB-promoted chromoplasts than from chloroplasts of lettuce leaves ( Morelli and Rodriguez-Concepcion, 2021 ).…”

Boosting pro-vitamin A content and bioaccessibility in leaves by combining engineered biosynthesis and storage pathways with high-light treatments

“…The physicochemical contexts and subcellular locations where carotenoids accumulate in plant cells highly influence bioaccessibility (Watkins and Pogson, 2020;Zheng et al, 2020). In the case of β-carotene, its bioaccessibility in lettuce artificial chromoplasts produced by crtB was doubled compared to that in chloroplasts (Morelli and Rodriguez-Concepcion, 2022). Recent results showed that extraplastidial β-carotene produced with a fungal pathway engineered in plant cells accumulates in cytosolic lipid droplets (Zheng et al, 2023), an environment that might be beneficial for bioaccessibility.…”

“…Recent results showed that extraplastidial β-carotene produced with a fungal pathway engineered in plant cells accumulates in cytosolic lipid droplets (Zheng et al, 2023), an environment that might be beneficial for bioaccessibility. To test whether the extraplastidial β-carotene produced with our bacterial pathway might be more bioaccessible, we performed an in vitro assay developed in our lab (Morelli and Rodriguez-Concepcion, 2022) to estimate the bioaccessibility of carotenoids in leaf samples. N. benthamiana leaves were agroinfiltrated with HE (a control for β-carotene exclusively present in chloroplasts), p-crtB (in which β-carotene is stored in the PG of artificial chromoplasts), HEcBIY (with β-carotene accumulated in chloroplasts but also in extraplastidial locations) or HEBIY (in which β-carotene is accumulated in both artificial chromoplasts and extraplastidial locations).…”