水稻吸收、运输锌及其籽粒富集锌的机制

Mechanism of Zn Uptake,Translocation in Rice Plant and Zn-enrichment in Rice Grain

锌是人体必需而又易缺乏的营养元素。在粮食作物可食部位生物强化锌被认为是解决人体缺锌的最有潜力的途径。水稻根吸收锌可分为分泌麦根酸等根系分泌物将土壤颗粒中的金属离子活化和重金属转运蛋白把锌离子转运进植株根部两个过程,ZIP家族基因在后一过程中发挥重要作用。水稻锌在木质部中运输主要以离子态为主,也可同有机酸、尼克酰胺等配体协同运输。地上部锌通过韧皮部再转运到新生组织或装载进入籽粒,水稻韧皮部再转运能力是影响籽粒富锌的关键因素,而锌大量累积在糊粉层中或与植酸等结合后,大大降低了锌的生物有效性。研究粮食作物籽粒富锌机制,利用现代分子生物技术生物强化籽粒中的锌含量,对满足人类锌营养健康具有重要意义。综述了锌在植物体内的生理功能,水稻对锌的吸收、运输和再转运,锌装载进入籽粒,锌在植物体内的分布与赋存形态,以及锌在粮食作物中的生物强化等最新研究进展。

Zinc （Zn） is an essential but easy to be deficient micronutrient for human beings around the world. Zinc biofortification through staple food crops is suggested as an effective way to solve this problem. Unveiling the mechanism of Zn uptake, translocation and accumulation in edible parts is regarded as a critical step. Zinc uptake by rice roots largely depends on： 1） excretions （such as mugineic acid） activating the Zn ion, and 2） the heavy metal transporter uptaking the Zn2＋ into root symplasm, among which the ZIP gene families are reported to be very important. Zinc transport in xylem are mainly in the forms of ions, but also reported to be associated with organic acid, nicotinamide and other ligands. Retranslocation of Zn by phloem takes a vital role in the Zn accumulation in rice grains. Preferential localization of Zn in aleurone and/or association of Zn with phytic acid significantly reduce the Zn bioavailability in rice. Unveiling the mechanism of Zn accumulated in grains and improving the Zn density in rice grains through modern biotechnology may convert the problem of Zn deficiency for human beings. This review summarized the latest progresses in researches on physiological function of Zn in rice, Zn uptake, translocation, remobilization, Zn distribution and in vivo speciation in rice, as well as Zn biofortification in food crops.