Overexpression of TaLAX3-1B alters the stomatal aperture and improves the salt stress resistance of tobacco

Background: Stomata, which play important roles in both optimizing photosynthesis efficiency and adapting to stress, are closely related to IAA and ABA. In plants, the auxin influx carrier LAX3 has been found to play roles in development and stress tolerance. However, the function of LAX3 in stomata and in response to salt stress remains largely unknown. Methods and results: Here, we show that overexpression of wheat TaLAX3-1B in tobacco results in a decrease in stomatal aperture and a relatively closed state of the stomata. In addition, the stomatal movement of the OxTaLAX3-1B lines was less sensitive to ABA than that of the WT. Consistently, compared with the WT, the OxTaLAX3-1B lines showed significantly higher expression of stomate-, IAA- and ABA-related genes and endogenous IAA and ABA contents. Furthermore, compared with the WT, the OxTaLAX3-1B lines exhibited higher proline content, salt stress-related gene expression and ROS antioxidant enzyme activity but lower MDA content and ROS accumulation after salt treatment. Conclusions: The present results suggest that TaLAX3-1B plays a positive role in regulating stomatal closure and enhancing salt stress tolerance.