Yang An, Li Yansu, Xu Yunyuan, Zhang Wen-Hao
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China.
J Exp Bot. 2013 Nov;64(16):5009-20. doi: 10.1093/jxb/ert290. Epub 2013 Sep 7.
Iron (Fe) is one of the essential mineral elements for plant growth and development. Acquisition of Fe by plants is mediated by a complex network involving Fe mobilization, uptake by root cells, and transport within plants. Here, we evaluated the role of a previously clarified gene encoding a receptor-like protein from rice, OsRMC, in the regulation of Fe acquisition by comparing Fe concentration, biomass, and expression patterns of genes associated with Fe mobilization and transport in wild-type (WT) rice with those in OsRMC overexpression and RNA interference (RNAi) knockdown transgenic rice plants. Expression of OsRMC was upregulated in both shoots and roots upon exposure of WT to Fe-deficient medium. Expression levels of OsRMC were positively correlated with Fe concentration in rice plants under both Fe-sufficient and Fe-deficient conditions such that overexpression and RNAi lines had higher and lower Fe concentration in both roots and shoots than WT plants, respectively. Moreover, overexpression of OsRMC conferred greater accumulation of Fe in mature seeds under Fe-sufficient conditions. OsRMC may also play a role in regulation of Fe deficiency-induced changes in root growth, as evidenced by greater and smaller root systems of OsRMC overexpression lines and RNAi lines than WT under Fe-deficient conditions, respectively. Several Fe deficiency-responsive genes including OsDMAS1, OsNAS1, OsNAS2, OsNAAT1, OsIRT1, OsYSL15, and OsIRO2 were up- and downregulated in OsRMC-overexpressing and RNAi plants compared with WT rice plants. These novel findings highlight an important role of OsRMC played in mediation of Fe acquisition and root growth in rice, particularly under Fe-deficient conditions.
铁（Fe）是植物生长发育所必需的矿质元素之一。植物对铁的获取由一个复杂的网络介导，该网络涉及铁的活化、根细胞的吸收以及在植物体内的运输。在此，我们通过比较野生型（WT）水稻与OsRMC过表达和RNA干扰（RNAi）敲低转基因水稻植株中铁的浓度、生物量以及与铁活化和运输相关基因的表达模式，评估了水稻中一个先前已阐明的编码类受体蛋白的基因OsRMC在铁获取调控中的作用。将WT暴露于缺铁培养基后，OsRMC在地上部和根部的表达均上调。在铁充足和缺铁条件下，水稻植株中OsRMC的表达水平均与铁浓度呈正相关，因此过表达和RNAi株系在根和地上部的铁浓度分别高于和低于WT植株。此外，在铁充足条件下，OsRMC的过表达使成熟种子中铁的积累量增加。OsRMC也可能在调控缺铁诱导的根系生长变化中发挥作用，证据是在缺铁条件下，OsRMC过表达株系和RNAi株系的根系分别比WT的根系大或小。与WT水稻植株相比，包括OsDMAS1、OsNAS1、OsNAS2、OsNAAT1、OsIRT1、OsYSL15和OsIRO2在内的几个缺铁响应基因在OsRMC过表达和RNAi植株中上调或下调。这些新发现突出了OsRMC在介导水稻铁获取和根系生长中所起的重要作用，特别是在缺铁条件下。
