Identification and Characterization of the Core Region of Promoter Activity and Its Upstream Regulatory Proteins.

Drought-induced 19 (Di19) family genes play important roles in plant growth, development, and environmental stress responses. However, little is known about this family in maize. The upstream regulatory network of Di19 genes remains poorly understood in plant stress response, especially. In this study, seven ZmDi19 genes were identified, and sequence alignment, gene structure, and phylogenetic analysis was conducted. According to the phylogenetic analysis, the promoter was cloned and multiple putative stress-responsive -acting elements (CAEs) were found in the promoter region. The transient transformation assay indicated that firefly luciferase (LUC)-expressed activity driven by the promoter can be significantly induced by drought stress. A 450 bp core region of promoter was identified, and 28 upstream regulatory proteins were screened using yeast one-hybird (Y1H) system. According to the functional annotation, some genes were related to photosynthesis, light response, and water transport, which may suggest the important roles of these genes in drought response. Particularly, five members that may be involved in drought response exhibited strong binding activity to the core region of the promoter. This study laid an important foundation for further revealing the molecular mechanisms and regulatory network of Di19 genes in drought stress response.