Abstract: An AgNAC1 gene encoding NAC transcription factor was cloned from Apium graveolens‘Liuhe Huangxinqin’and‘Ventura’by RT-PCR method，respectively. The amino acid sequences，protein physicochemical properties，phylogenetic relationships and spatial structures of AgNAC1 were analyzed. The relative expression levels of AgNAC1 under different abiotic stresses were detected by quantitative real-time PCR. The results showed that the lengths of open reading frame of AgNAC1 genes in‘Liuhe Huangxinqin’and‘Ventura’were both 957 bp and encoded 318 amino acids. The relative molecular masses of AgNAC1 were 36.89 and 36.77 kD，with theoretical pI about 5.94 and 5.78，respectively. The homologous alignment and phylogenetic analysis of AgNAC1 with other NAC TFs in different plants revealed that AgNAC1 and DcNAC of Daucus carota belong to the same branch of evolutionary distance. AgNAC1 had the closest genetic relation with DcNAC. The prediction of protein functional domain showed that AgNAC1 protein contains multiple α-helix and β-turn secondary structure units. Quantitative real-time PCR analysis indicated that the AgNAC1 was tissue-specific in celery，and it mainly expressed in leaf. In addition，AgNAC1 responded to heat，cold，drought and salt stresses. The expression levels of AgNAC1 in‘Liuhe Huangxinqin’peaked at 24 h under high temperature treatment. The expression levels of AgNAC1 in‘Ventura’were higher than that of the control at 2 h and 8 h under high temperature treatment，low temperature and salt treatments，showing a trend of first decrease and then increase. The expression level of AgNAC1 was the highest at 4 h under drought treatment.

Key words: Apium graveolens, NAC transcription factor, expression analysis, leaf, abiotic stress