miRNA mediated regulation of NAC transcription factors in plant development and environment stress response

NAC genes comprise one of the largest families of plant transcription regulators that are known to play crucial roles in various developmental processes and stress responses. Evolutionary expansion of the gene family in land plants probably added to the functional diversity of the gene family. The ongoing research has analyzed the differential expression patterns of the NAC transcription factors under various stresses for determining their plausible role during adaptive stress response in plants. However, the complex molecular mechanism regulating NAC gene expression and function is still elusive. The discovery of miRNAs, as a novel class of regulatory factors, has shed new light on the regulatory mechanisms that define the functional domains of the transcription factors. In this context studies on miRNA-mediated regulation of NAC gene expression in plant development have provided critical evidence for multi-layered control of the transcription factors. The review describes the divergent role of NAC transcription factors, which were initially thought to be only involved in vasculature development in plants. The structural features of the NAC transcription factors and the evolution of the gene family have also been discussed. Special focus is placed on the regulation of NAC-TFs by miRNAs to understand the developmental networks operating in the plants in response to abiotic stress and hormone cues.