Abstract:The function of IQM3 gene from Arabidopsis thaliana was analyzed. The ressults showed that the putative promoter region of IQM3 contained cis-acting regulatory elements involved in response to environmental changes, such as light, phytohormones and abiotic-stress. IQM3 gene strongly expressed in different organs of 6-week-old plant, such as flower, rosette leaf, cauline leaf, stem, and root, but weekly in pods. Mutants iqm3-1 and iqm3-2 inserted T-DNA of IQM3 gene had been found to be loss-of-function and over-expression line, respectively, by RT-PCR analysis. Phenotypic characterization of the mutants indicated that IQM3 gene related with seed germination and cotyledon expansion.