The complete open reading frame of OsPIN1a was amplified through reverse transcriptase- polymerase chain reaction(RT-PCR) based on the sequence deposited in GenBank to explore the relationship between the auxin efflux protein OsPIN1a and the negative phototropism of rice roots. Sequencing results showed that the GC content of OsPIN1a was 65.49%. The fusion expression vector pCAMBIA-1301-OsPIN1a::GFP containing the OsPIN1a gene and a coding green fluorescent protein(gfp) gene was constructed. The fusion vector was transferred into onion epidermal cells by Agrobacterium tumefaciens transformation. The transient expression of OsPIN1a-GFP was mainly located in the nucleus and cell membrane. Moreover, the transgenic plants were obtained by Agrobacterium-mediated genetic transformation. Molecular detection performed by using PCR and β-glucuronidase staining showed that the target construct was integrated into the genome of rice. The negative phototropic curvatures of the transgenic rice roots were higher than those of the wild type. Similarly, the expression levels of OsPIN1a in the transgenic plants were considerably higher than those in the wild-type plants. These results suggest that OsPIN1a is crucial in the negative phototropic curvature of rice roots. The complete open reading frame of OsPIN1a was amplified through reverse transcriptase-polymerase chain reaction (RT-PCR) based on the sequence deposited in GenBank to explore the relationship between the auxin efflux protein OsPIN1a and the negative phototropism of rice roots. Sequencing results showed that the fusion expression vector pCAMBIA-1301-OsPIN1a :: GFP containing the OsPIN1a gene and a coding green fluorescent protein (gfp) gene was constructed. The fusion vector was transferred into onion epidermal cells by Agrobacterium tumefaciens transformation. The transient expression of OsPIN1a-GFP was mainly located in the nucleus and cell membrane. Furthermore, the transgenic plants were obtained by Agrobacterium-mediated genetic transformation. Molecular detection performed by using PCR and β-glucuronidase staining showed the the target construct was integrated into the genome of rice. The negative phototropic curvatures of the transgenic rice roo ts are higher than those of the wild type. These results suggest that OsPIN1a is crucial in the negative phototropic curvature of rice roots.