ZmLBD5 Increases Drought Sensitivity by Suppressing ROS Accumulation in Arabidopsis

Drought stress is known to significantly limit crop growth and productivity. Lateral organ boundary domain (LBD) transcription factors-particularly class-I members-play essential roles in plant development and biotic stress. However, little information is available on class-II genes related to abiotic stress in maize. Here, we cloned a maize class-II LBD transcription factor, and identified its function in drought stress. Transient expression, transactivation, and dimerization assays demonstrated that was localized in the nucleus, without transactivation, and could form a homodimer or heterodimer. Promoter analysis demonstrated that multiple drought-stress-related and ABA response cis-acting elements are present in the promoter region of . Overexpression of in Arabidopsis promotes plant growth under normal conditions, and suppresses drought tolerance under drought conditions. Furthermore, the overexpression of increased the water loss rate, stomatal number, and stomatal apertures. DAB and NBT staining demonstrated that the reactive oxygen species (ROS) decreased in -overexpressed Arabidopsis. A physiological index assay also revealed that SOD and POD activities in -overexpressed Arabidopsis were higher than those in wild-type Arabidopsis. These results revealed the role of in drought stress by regulating ROS levels.