(800-46) An in vivo GA- and ABA-responsive dual-luciferase reporter system for simultaneous detection of GA and ABA responses, hormone crosstalk, and heat-stress response in rice
Professor National Taiwan University Taipei, Taipei, Taiwan (Republic of China)
Body of Abstract: GA and ABA are the primary phytohormones with antagonistic roles in controlling seeds' transition from embryogenesis to germination. The analytical determination provides accurate quantification of GA and ABA contents, but the extraction procedure is time-consuming, and the antagonism and dynamic changes between GA and ABA may not be detected. Therefore, simultaneous detection of GA and ABA responses during seed germination by a simple system is highly needed. To this end, a simple, sensitive, and reliable in vivo GA/ABA dual luciferase reporter system was established in this study. Transgenic rice harboring a firefly luciferase (firefly LUC) directed by a synthetic promoter consisting of two copies of the ABRC, together with a Renilla luciferase (Renilla LUC) directed by the GA-responsive Amy32b promoter, was generated. The sensitivity of GA- and ABA-responsive promoters and the possible crosstalk of exogenous plant hormones with endogenous GA and ABA responses were evaluated. Furthermore, the effect of sub-optimal, supra-optimal, and heat-stressed temperatures on the dynamic changes in GA/ABA response was investigated to simultaneously examine the antagonistic effects of GA and ABA during seed germination. This system is useful for studying the effects of exogenous factors (e.g., abiotic stresses, xenobiotics, and elicitors) and endogenous factors (e.g., developmental stages and tissues) on the dynamic changes in GA and ABA responses. Additionally, the current system may be applied to elucidate the role of genes crucial for signaling and antagonism of GA and/or ABA by stable transformation or transient expression in protoplasts.