Overexpression of the rice basic leucine zipper transcription factor OsbZIP12 confers drought tolerance to rice and makes seedlings hypersensitive to ABA

Abiotic stresses such as drought, high salinity, and cold are key factors in determining crop yield. Rice is a notoriously drought-susceptible crop due in part to its small root system. Abscisic acid (ABA) involves in abiotic stress resistance in plants. The basic leucine zipper (bZIP) transcription factors play important roles in the ABA signaling pathway in plants. OsbZIP12 is a member of the group E bZIP transcription factor family in rice (Oryza sativa). Expression of OsbZIP12 is induced by abiotic stresses and ABA as well as sugar in rice. It is rapidly and strongly induced by drought stress. Corresponding with expression patterns, several stress and sugar-associated cis-acting elements were found in the OsbZIP12 promoter region. Transgenic rice overexpressing OsbZIP12 showed significantly improved drought tolerance and hypersensitivity to ABA. The elevated levels of expression of the ABA responding LEA3 and Rab16 genes in transgenic rice may enhance drought tolerance. These results indicate that OsbZIP12 is a positive regulator of ABA signaling and drought stress tolerance in rice and that OsbZIP12 could be involved in crosstalk among stress, hormone, and sugar signaling. We propose that OsbZIP12 is an important player in rice for conferring ABA-dependent drought tolerance and has high potential for use in the genetic improvement of stress tolerance.