TaNAC8, a novel NAC transcription factor gene in wheat, responds to stripe rust pathogen infection and abiotic stresses

The plant-specific NAC domain proteins have been shown previously to play important roles in both abiotic and biotic stresses or in diverse developmental processes. In this research, the full-length cDNA sequence of a novel NAC (for (N) under bar AM, (A) under bar TAF1/2, (C) under bar UC2) transcription factor gene, designated as TaNAC8, was isolated from wheat (Triticum aestivum) using in silico cloning, reverse transcription polymerase chain reaction and 3' rapid amplification of cDNA ends PCR methods. TaNAC8 was highly homologous to the rice OsNAC8 gene and predicted to encode a protein of 481 amino acids. The encoded TaNAC8 protein contained a NAC domain in the N-terminus and a transmembrane helices motif in the C-terminus. Using the yeast one-hybrid assay, we detected that the C-terminal region of the TaNAC8 protein had transcriptional activity. TaNAC8 was expressed strongly in the developing wheat seeds, but weakly in stems and flowers. The expression of TaNAC8 in leaves was induced by the infection of the stripe rust pathogen (Puccinia striiformis f. sp. tritici) in the incompatible interaction at 24 h post inoculation, and also by treatments with methyl jasmonate and ethylene. However, salicylic acid and abscisic acid had no any significant effect on the gene expression. Several environmental stimuli, including high salinity, PEG (polyethylene glycol) treatment, and low-temperature, also enhanced the TaNAC8 expression. These results suggest that the novel TaNAC8 protein functions as a transcriptional activator involved in wheat defense responses to abiotic and biotic stresses. (C) 2010 Elsevier Ltd. All rights reserved.