Abstract: Based on the cDNA subtraction library which had been constructed to identify differentially expressed genes in peel pitting of citrus fruit, the full-length cDNA sequence of CsNAC homologous to NAC gene family was isolated from navel orange (Citrus sinensis Osbeck) by RACE (rapid amplification of cDNA ends). CsNAC is of 1 203 nucleotides encoding a protein of 305 amino acids. The calculated molecular weight of the CsNAC protein was 35.2 kDa and theoretical isoelectric point was 6.72. Sequence analysis showed that the CsNAC protein had a strikingly conserved region at the N-terminus, which is considered as the characteristic of NAC protein family. Phylogenetic analysis confirmed CsNAC belonged to the ATAF subfamily, which plays an important role in response to stress stimuli. The expression of CsNAC was markedly enhanced in the pitting peel compared to healthy peel during the storage by real-time quantitative PCR, indicating that CsNAC is involved in the development of the peel pitting of navel orange fruits.

Key words: Citrus sinensis Osbeck, cloning, expression, CsNAC