Hexaploid wheat is an important cereal crop that has been targeted to enhance grain micronutrient content including zinc (Zn) and iron (Fe). In this direction, modulating the expression of plant transporters involved in Fe and Zn homeostasis has proven to be one of the promising approaches. The present work was undertaken to identify wheat zinc-induced facilitator-like (ZIFL) family of transporters. The wheat ZIFL genes were characterized for their transcriptional expression response during micronutrient fluctuations and exposure to multiple heavy metals. The genome-wide analyses resulted in identification of fifteen putative TaZIFL-like genes, which were distributed only on Chromosome 3, 4 and 5. Wheat ZIFL proteins subjected to the phylogenetic analysis showed the uniform distribution along with rice, Arabidopsis and maize. In-silico analysis of the promoters of the wheat ZIFL genes demonstrated the presence of multiple metal binding sites including those which are involved in Fe and heavy metal homeostasis. Quantitative real-time PCR analysis of wheat ZIFL genes suggested the differential regulation of the transcripts in both roots and shoots under Zn surplus and also during Fe deficiency. Specifically, in roots, TaZIFL2.3, TaZIFL4.1, TaZIFL4.2, TaZIFL5, TaZIFL6.1 and TaZIFL6.2 were significantly up-regulated by both Zn and Fe. This suggested that ZIFL could possibly be regulated by both the nutrient stress in a tissue specific manner. When exposed to heavy metals, TaZIFL4.2 and TaZIFL7.1 show significant up-regulation, whereas TaZIFL5 and TaZIFL6.2 remained almost unaffected. This is the first report for detailed analysis of wheat ZIFL genes. ZIFL genes also encode for transporter of mugineic acid (TOM) proteins, that are involved in the release of phytosiderophores to enhance Fe/Zn uptake. The detailed expression analysis suggests the varying expression patterns during development of wheat seedlings and also against abiotic/biotic stresses. Overall, this study will lay foundation to prioritize functional assessment of the candidate ZIFL as a putative TOM protein in wheat.

中文翻译：

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小麦锌诱导的类似促进子的转运蛋白的重叠转录表达应答强调了铁和锌胁迫期间的重要作用。

六倍体小麦是重要的谷物作物，其目标是提高谷物的微量营养素含量，包括锌（Zn）和铁（Fe）。在这个方向上，调节参与铁和锌稳态的植物转运蛋白的表达已被证明是有前途的方法之一。开展本工作以鉴定小麦锌诱导的类似促进子（ZIFL）的转运蛋白家族。小麦ZIFL基因的特征在于其在微量营养素波动和暴露于多种重金属期间的转录表达响应。全基因组分析确定了15个推定的TaZIFL样基因，这些基因仅分布在3号，4号和5号染色体上。经过系统进化分析的小麦ZIFL蛋白与水稻，拟南芥和玉米一样分布均匀。小麦ZIFL基因启动子的计算机分析表明存在多个金属结合位点，包括那些与铁和重金属稳态有关的结合位点。小麦ZIFL基因的实时定量PCR分析表明，在锌过量和铁缺乏时，根和芽中转录本的差异调节。具体地，在根中，Zn和Fe均显着上调了TaZIFL2.3，TaZIFL4.1，TaZIFL4.2，TaZIFL5，TaZIFL6.1和TaZIFL6.2。这表明ZIFL可能可以通过组织特定方式的两种营养胁迫来调节。当暴露于重金属时，TaZIFL4.2和TaZIFL7.1表现出明显的上调，​​而TaZIFL5和TaZIFL6.2几乎不受影响。这是首次详细分析小麦ZIFL基因的报告。ZIFL基因还编码古柯酸（TOM）蛋白的转运蛋白，该蛋白与植物铁载体的释放有关，以增强铁/锌的吸收。详细的表达分析表明，在小麦幼苗发育过程中，以及针对非生物/生物胁迫的表达模式都有所不同。总的来说，这项研究将为优先考虑候选ZIFL作为小麦TOM蛋白质的功能评估奠定基础。