PDF(Pubmed)
Abstract：
Wheat is one of the most important food crops globally, and understanding the regulation of grain size is crucial for wheat breeding to achieve a higher grain yield. MicroRNAs (miRNAs) play vital roles in plant growth and development. However, the miRNA-mediated mechanism underlying grain size regulation remains largely elusive in wheat. Here, we report the characterization and functional validation of a miRNA, TamiR397a, associated with grain size regulation in wheat. The function of three TaMIR397 homoeologs was determined through histochemical β-glucuronidase-dependent assay. MiRNA expression was detected using quantitative reverse transcription polymerase chain reaction (qRT-PCR), and the function of TamiR397a was validated through its transgenic overexpression and repression in wheat. It was found that TaMIR397-6A and TaMIR397-6B encode active TamiR397a. The expression profiling indicated that TamiR397a was differentially expressed in various tissues and gradually up-regulated during grain filling. The inhibition of TamiR397a perturbed grain development, leading to a decrease in grain size and weight. Conversely, the overexpression of TamiR397a resulted in increased grain size and weight by accelerating the grain filling process. Transcriptome analysis revealed that TamiR397a regulates a set of genes involved in hormone response, desiccation tolerance, regulation of cellular senescence, seed dormancy, and seed maturation biological processes, which are important for grain development. Among the down-regulated genes in the grains of the TamiR397a-overexpressing transgenic plants, 11 putative targets of the miRNA were identified. Taken together, our results demonstrate that TamiR397a is a positive regulator of grain size and weight, offering potential targets for breeding wheat with an increased grain yield.
摘要：
小麦是全球最重要的粮食作物之一,了解籽粒大小的调节对于小麦育种获得更高的籽粒产量至关重要。MicroRNAs(miRNAs)在植物生长发育中发挥重要作用。然而,miRNA介导的机制在小麦中的籽粒大小调节仍然很大程度上难以捉摸。这里,我们报告了miRNA的表征和功能验证，TamiR397a,与小麦粒级调节有关。通过组织化学β-葡糖醛酸糖苷酶依赖性测定确定了三种TaMIR397同源物的功能。使用定量逆转录聚合酶链反应（qRT-PCR）检测miRNA表达，通过TamiR397a在小麦中的转基因过表达和抑制，验证了其功能。发现TaMIR397-6A和TaMIR397-6B编码活性TamiR397a。表达谱表明TamiR397a在各种组织中差异表达，并在籽粒灌浆过程中逐渐上调。TamiR397a的抑制扰乱了谷物发育，导致晶粒尺寸和重量的减少。相反，TamiR397a的过表达通过加速籽粒灌浆过程导致籽粒大小和重量增加。转录组分析显示，TamiR397a调节一系列参与激素反应的基因，耐干燥性，细胞衰老的调节，种子休眠,和种子成熟的生物过程，这对粮食发展很重要。在TamiR397a过表达转基因植物的谷粒中下调的基因中，鉴定了miRNA的11个推定靶标。一起来看,我们的结果表明，TamiR397a是晶粒尺寸和重量的正调节剂，为育种小麦提供潜在的目标，提高谷物产量。
