Maize ABP2 enhances tolerance to drought and salt stress in transgenic Arabidopsis

Abiotic stresses, especially drought and salt, severely affect maize production, which is one of the most important cereal crops in the world. Breeding stress-tolerant maize through biotechnology is urgently needed to maintain maize production. Therefore, it is important to identify new genes that can enhance both drought and salt stress tolerance for molecular breeding. In this study, we identified a maize ABA (abscisic acid)-responsive element (ABRE) binding protein from a 17-day post-pollination (dpp) maize embryo cDNA library by yeast one-hybrid screen using the ABRE2 sequence of the maize Cat1 gene as bait. This protein, designated, ABRE binding protein 2 (ABP2), belongs to the bZIP transcription factor family. Endogenous expression of ABP2 in maize can be detected in different tissues at various development stages, and can be induced by drought, salt, reactive oxygen species (ROS)-generating agents, and ABA treatment. Constitutive expression of ABP2 in transgenic Arabidopsis plants enhanced tolerance to drought and salt stress, and increased sensitivity to ABA. In exploring the mechanism by which ABP2 can stimulate abiotic stress tolerance, we found that ROS levels were reduced and expression of stress-responsive and carbon metabolism-related genes was enhanced by constitutive ABP2 expression in transgenic plants. In short, we identified a maize bZIP transcription factor which can enhance both drought and salt tolerance of plants.