Centre for Crop Health, University of Southern Queensland, Toowoomba, Queensland, Australia.
School of Agriculture, Food and Wine, Faculty of Sciences, University of Adelaide, Urrbrae, South Australia, Australia.
Physiol Plant. 2022 Jan;174(1):e13612. doi: 10.1111/ppl.13612. Epub 2021 Dec 30.
Zinc (Zn) is an important micronutrient in the human body, and health complications associated with insufficient dietary intake of Zn can be overcome by increasing the bioavailable concentrations in edible parts of crops (biofortification). Wheat (Triticum aestivum L) is the most consumed cereal crop in the world; therefore, it is an excellent target for Zn biofortification programs. Knowledge of the physiological and molecular processes that regulate Zn concentration in the wheat grain is restricted, inhibiting the success of genetic Zn biofortification programs. This review helps break this nexus by advancing understanding of those processes, including speciation regulated uptake, root to shoot transport, remobilisation, grain loading and distribution of Zn in wheat grain. Furthermore, new insights to genetic Zn biofortification of wheat are discussed, and where data are limited, we draw upon information for other cereals and Fe distribution. We identify the loading and distribution of Zn in grain as major bottlenecks for biofortification, recognising anatomical barriers in the vascular region at the base of the grain, and physiological and molecular restrictions localised in the crease region as major limitations. Movement of Zn from the endosperm cavity into the modified aleurone, aleurone and then to the endosperm is mainly regulated by ZIP and YSL transporters. Zn complexation with phytic acid in the aleurone limits Zn mobility into the endosperm. These insights, together with synchrotron-X-ray-fluorescence microscopy, support the hypothesis that a focus on the mechanisms of Zn loading into the grain will provide new opportunities for Zn biofortification of wheat.
锌（Zn）是人体中的一种重要微量元素，通过增加可食用作物部分的生物可利用浓度（生物强化），可以克服因膳食中锌摄入量不足而引起的健康并发症。小麦（Triticum aestivum L）是世界上消费最多的谷物作物；因此，它是锌生物强化计划的理想目标。对调节小麦籽粒中锌浓度的生理和分子过程的了解受到限制，这抑制了遗传锌生物强化计划的成功。本综述通过深入了解这些过程，包括受形态调节的摄取、根到茎的运输、再利用、籽粒装载以及锌在小麦籽粒中的分布，有助于打破这种联系。此外，还讨论了小麦遗传锌生物强化的新见解，在数据有限的情况下，我们还借鉴了其他谷物和铁分布的信息。我们认为，籽粒中锌的装载和分布是生物强化的主要瓶颈，认识到籽粒基部血管区域的解剖学障碍以及局部化在褶皱区域的生理和分子限制是主要限制。Zn 从胚乳腔向改良糊粉层、糊粉层然后向胚乳的移动主要受 ZIP 和 YSL 转运蛋白调节。在糊粉层中，Zn 与植酸的络合限制了 Zn 向胚乳的迁移。这些见解，加上同步加速器 X 射线荧光显微镜，支持这样一种假设，即关注 Zn 加载到籽粒中的机制将为小麦的 Zn 生物强化提供新的机会。
