SsNAC23‚ a member of the NAC domain protein family‚ is associated with cold‚ herbivory and water stress in sugarcane

The NAC (NAM/ATAF1/2/CUC) domain protein family is widely distributed in plants, and some of their members are regulated by biotic and abiotic stress. Using the SUCEST sugarcane EST database, we have identified 26 members of the NAC domain protein family, referred to collectively as Saccharum sp. NACs (SsNACs). Several SsNACs genes displayed a similar pattern of tissue/organ expression. One of these, SsNAC23, was found to be induced by chilling stress. SsNAC23 showed strong similarity to the Arabidopsis ATAF1 and rice OsNAC6 proteins, which have been phylogenetically classified into dicot and monocot ATAF sub-subfamilies, respectively. Molecular modeling of the SsNAC23 3-D structure and its nuclear localization suggest that this protein has conserved transcription factor domains. The expression of SsNAC23 was strongly induced at 4 °C but not at 12 °C, indicating that this gene is involved in the response to extreme low temperature stress. SsNAC23 was also induced by water stress and herbivory. The role of SsNAC23 in sugarcane plants subjected to stress stimuli is discussed.