Transcript level characterization of a cDNA encoding stress regulated NAC transcription factor in the mangrove plant Avicennia marina

NAC transcription factors are a family of functionally diverse proteins responsive to biotic and abiotic stresses. A full-length cDNA isolated from the salt stressed mangrove plant Avicennia marina showed high sequence identity to NAC proteins induced upon biotic stress in tomato and potato. The predicted protein sequence had all the highly conserved sub domains characteristic of NAC domain containing proteins. Northern analysis for AmNAC1 expression under tolerable (250 mM) concentration of NaCl revealed up regulation of the transcript after 48 h and higher transcript level after 10 days of treatment. Induction of AmNAC1 after 12 h of ABA treatment was similar to the treatment with stressful (500 mM) concentration of NaCl. The results suggest the involvement of AmNAC1 in early salt stress response and long-term adjustment to salt, besides a role for ABA in its expression under salt stress conditions.