Abstract: In the present study，three novel NAC genes，CmNAC83，PtNAC83 and ClNAC83，were cloned by in silico cloning and RT-PCR approaches from seedlings of pomelo[Citrus maxima（Burm.）Merr.]，trifoliate orange[Poncirus trifoliata（L.）Raf. ]and lemon[Citrus limon（L.）Burm. f.]. The expression patterns of these genes were analyzed by Real-time quantitative PCR（qRT-PCR）under the stress of ABA，drought，cold and salt. The results showed that the full length of cDNA sequence of all the three genes were 841 bp and the open reading frame（ORF）were 750 bp which encoded three polypeptides of 249 amino acids. The molecular weight of the three proteins were 24.18，28.00 and 28.15 kD，with isoelectric point about 9.02，9.31 and 9.30 respectively. The three novel proteins contained N-terminal conserved domains of NAC family. The phylogenetic analysis showed that the three proteins have the highest similarity with NAC22 from Malus × domestica，and Its belongs to the SENU5 subfamily in NACfamily. The qRT-PCR analysis indicated that the expressions of three NAC83 genes were induced by stress of ABA，drought，cold and salt，but they were differently expressed in different citrus species. The results of this paper suggested that CmNAC83，PtNAC83 and ClNAC83 were new members of the NAC gene family，and they might play important roles in citrus in response to abiotic stress.

Key words: pomelo, trifoliate orange, lemon, NAC83, cloning, expression analysis