Identification and Validation of miRNAs Associated with the Resistance of Maize (<i>Zea mays L</i>.) to <i>Exserohilum turcicum</i>

<div><p>Northern leaf blight, caused by the fungus <i>Exserohilum turcicum</i> (Pass.), is a major disease of maize (<i>Zea mays</i> L.). MicroRNAs (miRNAs) have been recently reported as gene expression regulators related to several stress responses; however, evidence of the role of miRNAs in plant response to biotic stresses is limited. In this study, the miRNA expression patterns in maize in response to <i>E. turcicum</i> stress were investigated using a plant miRNA microarray platform. A total of 118 miRNAs were detected in mock- and <i>E. turcicum</i>-inoculated leaves. Among these miRNAs, miR530, miR811, miR829, and miR845 were identified as new miRNAs in maize through a homology-based approach. The secondary structures and putative targets of these miRNAs were also predicted. In addition, four miRNAs were differentially regulated in response to <i>E. turcicum</i>: miR811, miR829, miR845, and miR408. The functional annotation of the predicted targets indicated that these stress-responsive miRNAs regulate metabolic, morphologic, and physiologic adaptations in maize seedlings at the post-transcriptional level. Four targets were negatively correlated with their corresponding miRNAs (miR811, miR829, and miR408). Furthermore, we have demonstrated for the first time that miR811 and miR829 confers a high degree of resistance to <i>E. turcicum</i>, which can be used in maize breeding programs.</p>