Abstract
Northern leaf blight, caused by the fungus Exserohilum turcicum (Pass.), is a major disease of maize (Zea mays 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 E. turcicum stress were investigated using a plant miRNA microarray platform. A total of 118 miRNAs were detected in mock- and E. turcicum-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 E. turcicum: 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 E. turcicum, which can be used in maize breeding programs.
Highlights
Maize is one of the most important staple food crops in the world
Results miRNA Identified in Leaf Tissues by Microarray MiRNA microarray analysis of the samples from the 9-dpi leaves of E. turcicum- inoculated and mock-inoculated plant was performed to investigate the potential involvement of miRNAs in E. turcicum-infected maize
The remaining three targets (TC476222, TC525988, and TC523422) were uniformly expressed at different time points after E. turcicum infection. These results strongly suggest that miR811, miR829, and miR408 contribute to the E. turcicum stress response of maize
Summary
Maize is one of the most important staple food crops in the world. Maize diseases are a major limiting factor in its production. Among these diseases, Turcicum blight, caused by Exserohilum turcicum(E. turcicum), is considered as a severe disease especially in regions with cool climates, with temperatures ranging from 20uC to 25uC, relative humidity from 90% to 100%, and low luminosity [1]. In China, yield losses have approached approximately 50% in the northern regions where crops suffered overwhelming E. turcicum infections [2]. Compared with traditional chemical treatments, many recent studies increasingly concentrated on host plant resistance, which is a more effective and economical way of controlling leaf blight diseases. It is of great importance to resort to identifying new resistance sources from artificial and natural inoculation, and to determining the resistance types and levels possessed by the available breeder’s materials and introduced germplasms
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