Chan-Rodriguez David, Walker Elsbeth L
Plant Biology Graduate Program, University of Massachusetts Amherst, Amherst, MA, United States.
Department of Biology, University of Massachusetts Amherst, Amherst, MA, United States.
Front Plant Sci. 2018 Feb 20;9:157. doi: 10.3389/fpls.2018.00157. eCollection 2018.
The micronutrient iron (Fe) is essential for photosynthesis, respiration, and many other processes, but it is only sparingly soluble in aqueous solution, making adequate acquisition by plants a serious challenge. Fe is a limiting factor for plant growth on approximately 30% of the world's arable lands. Moreover, Fe deficiency in humans is a global health issue, affecting 1.62 billion people, or about 25% of the world's population. It is imperative that we gain a better understanding of the mechanisms that plants use to regulate iron homeostasis, since these will be important targets for future biofortification and crop improvement strategies. Grasses and non-grasses have evolved independent mechanisms for primary iron uptake from the soil. The grasses, which include most of the world's staple grains, have evolved a distinct 'chelation' mechanism to acquire iron from the soil. Strong iron chelators called phytosiderophores (PSs) are synthesized by grasses and secreted into the rhizosphere where they bind and solubilize Fe(III). The Fe(III)-PS complex is then taken up into root cells via transporters specific for the Fe(III)-PS complex. In this study, 31 novel, uncharacterized striped maize mutants available through the Maize Genetics Cooperation Stock Center (MGCSC) were analyzed to determine whether their mutant phenotypes are caused by decreased iron. Many of these proved to be either pale yellow or white striped mutants. Complementation tests were performed by crossing the MGCSC mutants to and reference mutants. This allowed assignment of 10 alleles and 4 alleles among the novel mutants. In addition, four mutant lines were identified that are not allelic to either or . Three of these were characterized as being non-allelic to each other and as having low iron in leaves. These represent new genes involved in iron acquisition by maize, and future cloning of these genes may reveal novel aspects of the grass iron acquisition mechanism.
微量营养素铁（Fe）对于光合作用、呼吸作用及许多其他过程至关重要，但它在水溶液中的溶解度很低，这使得植物充分获取铁成为一项严峻挑战。铁是世界上约30%可耕地植物生长的限制因素。此外，人类缺铁是一个全球健康问题，影响着16亿人，约占世界人口的25%。我们必须更好地了解植物用于调节铁稳态的机制，因为这些机制将成为未来生物强化和作物改良策略的重要目标。禾本科植物和非禾本科植物已经进化出从土壤中吸收铁的独立机制。禾本科植物包括世界上大部分主要谷物，它们进化出了一种独特的“螯合”机制从土壤中获取铁。被称为植物铁载体（PSs）的强铁螯合剂被合成并分泌到根际，在那里它们结合并溶解Fe(III)。然后，Fe(III)-PS复合物通过对Fe(III)-PS复合物特异的转运蛋白被吸收到根细胞中。在本研究中，对通过玉米遗传合作种质中心（MGCSC）获得的31个新的、未表征的条纹玉米突变体进行了分析，以确定它们的突变表型是否由铁含量降低引起。其中许多被证明是浅黄色或白色条纹突变体。通过将MGCSC突变体与参考突变体杂交进行互补试验。这使得在新突变体中确定了10个等位基因和4个等位基因。此外，鉴定出四个突变系，它们与或都不是等位基因。其中三个被表征为彼此非等位且叶片中铁含量低。这些代表了参与玉米铁获取的新基因，未来对这些基因的克隆可能揭示禾本科植物铁获取机制的新方面。
