Genome-Wide Expression Profiling of Genes Associated with the Lr47-Mediated Wheat Resistance to Leaf Rust (Puccinia triticina)

Abstract

<i>Puccinia triticina</i> (<i>Pt</i>), the causal agent of wheat leaf rust, is one of the most destructive fungal pathogens threatening global wheat cultivations. The rational utilization of leaf rust resistance (<i>Lr</i>) genes is still the most efficient method for the control of such diseases. The <i>Lr47</i> gene introgressed from chromosome 7S of <i>Aegilops speltoides</i> still showed high resistance to the majority of <i>Pt</i> races collected in China. However, the <i>Lr47</i> gene has not been cloned yet, and the regulatory network of the <i>Lr47</i>-mediated resistance has not been explored. In the present investigation, transcriptome analysis was applied on RNA samples from three different wheat lines ("Yecora Rojo", "UC1037", and "White Yecora") carrying the <i>Lr47</i> gene three days post-inoculation with the epidemic <i>Pt</i> race THTT. A comparison between <i>Pt</i>-inoculated and water-inoculated "<i>Lr47</i>-Yecora Rojo" lines revealed a total number of 863 upregulated (<i>q</i>-value < 0.05 and log2foldchange > 1) and 418 downregulated (<i>q</i>-value < 0.05 and log2foldchange < -1) genes. Specifically, differentially expressed genes (DEGs) located on chromosomes 7AS, 7BS, and 7DS were identified, ten of which encoded receptor-like kinases (RLKs). The expression patterns of these <i>RLK</i> genes were further determined by a time-scale qRT-PCR assay. Moreover, heatmaps for the expression profiles of pathogenesis-related (<i>PR</i>) genes and several transcription factor gene families were generated. Using a transcriptomic approach, we initially profiled the transcriptional changes associated with the <i>Lr47</i>-mediated resistance. The identified DEGs, particularly those genes encoding RLKs, might serve as valuable genetic resources for the improvement of wheat resistance to <i>Pt</i>.