Abstract:ERA1 is an important gene in control of plant stomata opening.The conserved region of the gene has been chosen to construct RNAi vector to transform Arabidopsis.Growth,stomata aperture,detached leaf water loss and expression of ERA1 and some relative genes in transgenic plants were tested to evaluate how ERA1 down regulated by siRNA and affected Arabidopsis drought tolerance.The transgenic Arabidopsis showed clear repression of ERA1 gene expression.The transgenic plants are more sensitive to ABA comparing to wild type plant:the root is significant shorter and stomata aperture is smaller when treated with ABA.Moreover,the water loss rate of siRNA transgenic plant is lower than that of wild type control.However,siRNA transgenic plant has no visible unwanted growth phenotypes like observed in knock-out mutants.qRT-PCR analysis showed that repression of ERA1 by siRNA may activate some key stress responding gene like RAB18 and RD29B.This study found that use of siRNA to suppress the ERA1 gene can enhance Arabidopsis drought tolerance without any negative growth phenotype and may positively effect Arabidopsis drought tolerance through ABA pathway.