Characterization and expression patterns of the <i>NPR1</i>-like genes in maize.

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