Characterization and expression patterns of the NPR1-like genes in maize

The nonexpressor of pathogenesis-related 1 (NPR1) is the salicylic acid (SA) receptor, which plays an important regulatory role in plant immunity. However, the NPR1-like gene family in maize has not been comprehensively identified and analysed. In the present study, we identified gene structures, conserved motifs, cis-elements, and expression patterns in different tissues and organs, and under biotic and abiotic stresses. The NPR1-like proteins of different species are highly conserved during evolution. Many cis-acting elements have been identified in the promoter region of NPR1-like genes in maize, including elements that respond to growth and development, biotic and abiotic stresses, and plant hormones. Furthermore, the transcript abundance of all NPR1-like genes in maize changed significantly under abiotic treatments (cold, heat, salt, or drought treatments), phytohormone treatments and pathogen treatment (Ustilago maydis), indicating that they might be involved in biotic and abiotic stresses. In addition, ZmNPR1 is located in the cytoplasm, and overexpression of ZmNPR1 improves the resistance of maize plants to U. maydis. The findings of the present study might provide important information on under standing the complexity of the NPR1-like genes and their functions in maize.