Overexpression of the OsbZIP66 transcription factor enhances drought tolerance of rice plants

Drought stress is a major constraint of crop development and productivity. Plants have evolutionally developed several mechanisms at the molecular, cellular, and physiological levels to overcome drought stress. The basic leucine zipper (bZIP) transcription factor (TF) family members are starting to be concerned about their roles in drought stress responses. In this study, we functionally characterized OsbZIP66, a rice group-E bZIP TF, to be associated with rice drought tolerance mechanisms. Expression of OsbZIP66 was significantly induced upon treatments of rice plants with drought, high salinity, and ABA. These observations and the fact that the OsbZIP66 promoter contains ten ABA-responsive cis-elements suggest that OsbZIP66 is up-regulated by drought stress in an ABA-dependent manner. Overexpression of OsbZIP66 both in a whole plant body and specifically in roots enhanced drought tolerance of rice plants, indicating that the rice drought tolerance positively correlates with the expression levels of OsbZIP66. Thus, our results demonstrated that OsbZIP66 has a potential for use in biotechnological development of high-yielding rice plants under drought conditions.