Installing the neurospora carotenoid pathway in plants enables cytosolic formation of provitamin A and its sequestration in lipid droplets  

作　　者：Xiongjie Zheng Yasha Zhang Aparna Balakrishna Kit Xi Liew Hendrik N.J.Kuijer Ting Ting Xiao Ikram Blilou Salim Al-Babili 

机构地区：[1]The BioActives Lab,Center for Desert Agriculture(CDA),Biological and Environmental Science and Engineering(BESE),King Abdullah University of Science and Technology(KAUST),Thuwal 23955-6900,Saudi Arabia [2]The Laboratory of Plant Cell and Developmental Biology(LPCDB),Center for Desert Agriculture(CDA),Biological and Environmental Science and Engineering(BESE),King Abdullah University of Science and Technology(KAUST),Thuwal 23955-6900,Saudi Arabia [3]Present address:College of Plant Science and Technology,Bejing Key Laboratory for Agricultural Application and New Technique,Beijing University of Agriculture,Beijing 102206,China

出　　处：《Molecular Plant》2023年第6期1066-1081,共16页分子植物（英文版）

基　　金：supported by baseline funding and Competitive Research Grants(CRG 2017,CRG 2020)given to Salim Al-Babili from King Abdullah University of Science and Technology(KAUST).

摘　　要：Vitamin A deficiency remains a severe global health issue,which creates a need to biofortify crops with provitamin A carotenoids(PACs).Expanding plant cell capacity for synthesis and storing of PACs outside the plastids is a promising biofortification strategy that has been little explored.Here,we engineered PAC formation and sequestration in the cytosol of Nicotiana benthamiana leaves,Arabidopsis seeds,and citrus callus cells,using a fungal(Neurospora crassa)carotenoid pathway that consists of only three enzymes converting C5 isopentenyl building blocks formed from mevalonic acid into PACs,including β-carotene.This strategy led to the accumulation of significant amounts of phytoene and γ-and β-carotene,in addition to fungal,health-promoting carotenes with 13 conjugated double bonds,such as the PAC torulene,in the cytosol.Increasing the isopentenyl diphosphate pool by adding a truncated Arabidopsis hydroxymethylglutaryl-coenzyme A reductase substantially increased cytosolic carotene production.Engineered carotenes accumulate in cytosolic lipid droplets(CLDs),which represent a novel sequestering sink for storing these pigments in plant cytosol.Importantly,β-carotene accumulated in the cytosol of citrus callus cells was more light stable compared to compared with plastidialβ-carotene.Moreover,engineering cytosolic carotene formation increased the number of large-sized CLDs and the levels of β-apocarotenoids,including retinal,the aldehyde corresponding to vitamin A.Collectively,our study opens up the possibility of exploiting the high-flux mevalonic acid pathway for PAC biosynthesis and enhancing carotenoid sink capacity in green and non-green plant tissues,especially in lipid-storing seeds,and thus paves the way for further optimization of carotenoid biofortification in crops.

关 键 词：Neurospora crassa carotenoid biosynthesis provitamin A metabolic engineering synthetic metabolism cytosolic lipid droplets carotenoid sequestration carotenoid stability 

分 类 号：Q94[生物学—植物学]