马铃薯的叶酸生物强化

      世界卫生组织将营养素摄入不足或营养失衡称之为“隐性饥饿”。它是一种人体一时难以感觉到的状态，但如果忽视的话就可以导致智力发育障碍，劳动能力丧失、免疫力下降等各种疾病。当前，全球有近20亿人口面临“隐性饥饿”的威胁，直接经济损失可占发展中国家国民生产总值的3%-5%。每年因叶酸缺乏至少导致25万的婴儿出生缺陷。叶酸在生物体的一碳代谢过程中扮演重要角色。通过生物强化手段提高作物中叶酸的含量是解决叶酸缺乏症的有效策略。
      之前的研究表明，通过引入叶酸生物合成基因GTPCHI 和 ADCS实现水稻和番茄的生物强化的策略十分有效，然而，该策略在马铃薯块茎中并未显著增加叶酸的含量。近日，比利时根特大学的研究人员在转GTPCHI基因和 ADCS基因的基础上，又引入线粒体叶酸合成途径中的下游基因HPPK/DHPS 和/或FPGS，该策略能够使叶酸含量增加12倍，而且在块茎的储藏期内，叶酸含量能够保持相对稳定。该研究不仅为叶酸生物强化提供了新的策略，而且有望解决马铃薯消费群体的叶酸缺乏问题。
Molecular Plant, December 19, 2017
Folate biofortification of potato by tuber-specific expression of four folate biosynthesis genes
Authors
Jolien De Lepeleire, Simon Strobbe4, Jana Verstraete, Dieter Blancquaert, Lars Ambach, Richard G.F. Visser, Christophe Stove, Dominique Van Der Straeten
Abstract
Insufficient dietary intake of micronutrients, known as ‘hidden hunger’, is a devastating global burden, affecting 2 billion people. Deficiency of folates (vitB9), which are known to play a central role in C1-metabolism, causes birth defects in at least a quarter million people annually. Biofortification to enhance the level of naturally occurring folates in crop plants, proves to be an efficient and cost-effective tool in fighting folate deficiency. Previously, introduction of folate biosynthesis genes GTPCHI and ADCS, proven to be a successful biofortification strategy in rice and tomato, turned out to be insufficient to adequately increase folate levels in potato tubers.Here, we provide a proof-of-concept that additional introduction of HPPK/DHPS and/or FPGS, downstream genes in mitochondrial folate biosynthesis, enables augmentation of folates to satisfactory levels (12-fold) and ensures folate stability upon long term storage of tubers. In conclusion, this engineering strategy can serve as a model in the creation of folate accumulating potato cultivars, readily applicable in potato consuming populations suffering from folate deficiency.