Development Of Chemical-inducible Gene Expression System In Rice

Chemical-inducible expression system is a powerful tool for plant functionalgenomics and plant genetic engineering applications. To date, severalchemical-inducible expression systems have been developed for plant biologicalresearch. For example, a XVE system has been proved to strictly regulate geneexpression in Arabidopsis. However, most of the chemical-inducible expressionsystems are confined to application in dicotyledonous plants, such as Arabidopsis,tobacco etc. For monocots, like rice, although there were reports about inducibleexpression system, it is difficult to actually apply in rice functional gene researchbecause of the transport barriers of chemical inducers in rice. In this study, generegulation expression pattern of XVE system was studied in transgenic rice tissuesupon β-estradiol induction. We further developed a practical chemical-regulated geneexpression system in rice by combining the XVE with a high-efficiency site-specificrecombination system. By using GUS as the report gene, analyses of transgenic ricecallus and plants revealed that:1) the XVE system could strictly regulate theexpression of exogenous gene in rice tissues;2) XVE inducible system combined withthe site-specific recombination system, was capable of specifically mediating theexogenous gene fragments recombination in transgenic rice callus and transgenic riceplants;3) a modified site-specific recognition sequence significantly improved therecombination efficiency upon chemical induction, which could be used to regulategene expression or RNA interference. In conclusion, we have developed a practicalchemical-inducble system for rice functional gene study, as well as for production ofmarker-free transgenic rice plants.