Characterization of a vascular bundle localizing Gossypium hirsutum NAC4 transcription factor promoter for its role in environmental stress responses

We have studied the expression of GhNAC4, a NAC domain-containing transcription factor from Gossypium hirsutum. The expression of GhNAC4 was upregulated by ABA, cytokinin, JA, GA, auxin, and ethylene. Its expression was also highly induced by drought, osmotic stress, oxidative stress, salinity, high and low-temperature stress, and wounding. To corroborate these observations, we have conducted a spatio-temporal analysis of the promoter of the GhNAC4 gene, by using uidA (GUS) gene in a transcriptional fusion in transgenic tobacco. The GUS expression was mostly localized to the vascular bundles along with shoot apical meristem and guard cells. We also observed intense staining in other cells upon wounding. Sequence analysis of the promoter revealed the presence of several motifs pertaining to phytohormone responsiveness, stress-inducibility, light responsive, sugar-responsive and tissue-specificity. These data suggests that GhNAC4 is a vascular tissue localizing NAC transcription factor, which may act as a node integrating environmental stress signals for modulating plant growth and development with the aid of phytohormonal stimuli.\n\nKey messageGhNAC4 transcription factor from cotton, localizes to vascular bundles and is highly upregulated by phytohormones and environmental stresses.