SGTl (suppressor of the G₂ allele of skp1) is a required component in some signaling pathways mediated by disease resistance (R) genes in many plant species.In this study,a full-length cDNA encoding the SGT1 protein was isolated from Ipomoea trifida by RT-PCR and RACE,designated ItSGT1.ItSGT1 has an open reading frame of 1 087 bp encoding putative protein of 361 amino acid residues.The molecular weight of putative protein is 40.1 kD and its pI is 5.05.The predicted SGT1 protein contained typical SGT1 domains of TPR,VR1,CS,VR2 and SGS.The deduced amino acid of ItSGT1 showed higher degree of similarities with their orthologs in other plant species.Southern blot analyses revealed that SGT1 was a multi-copy gene in the I.trifida genome.Analysis of ItSGT1 expression at the mRNA level by semi-quantity RT-PCR showed that ItSGT1 was expressed in different tissues.