Keywords: 
• biochemistry molecular biology /
• primary auxin-responsive gene （Aux/IAA） /
• gene function /
• regulation mechanism /
• review

Abstract: Members of Aux/IAA gene family are responsive to primary auxin induction. ARF is a kind of regulating auxin response gene expression to regulate auxin primary function of gene transcription. By combining its response elements with the specificity of ARF, Aux/IAA is a transcription function to regulate primary auxin-responsive gene. This paper reviewed the recent advances in the structural characteristics, regulation mechanism and biological functions of Aux/IAAs. Aux/IAAs consisted of four conserved domains: Domains Ⅰ, Ⅱ, Ⅲ and Ⅳ. Domain Ⅰ was responsible for the protein inhibition of Aux/IAAs. With a leucine motif, Domain Ⅱ was capable of rapid protein stability. Domains Ⅲ and Ⅳ were responsible for protein dimerization （homo- and hetero-dimerization）. Aux/IAAs promoted the transcription of early genes by combining auxin response factors, and they regulated the expression of downstream genes in the process of auxin signal transduction. Different Aux/IAAs were expressed in different tissues and organisms. Also, the study of Aux/IAA mutants indicated that different Aux/IAAs had different functions due to differences in temporal and spatial expression and affinities with promoters of Aux/IAA genes to the ARF gene. Plant hormones and environmental factors also had important roles in regulating Aux/IAAs. ［Ch, 43 ref.］