Targeting transcription factors for plant disease resistance: shifting paradigm

Transcription factors (TFs) are regulatory proteins that have the ability to alter targeted gene expression either solely by themselves or as a part of the protein complex. Many such TFs have significant regulatory role in plant defence. Being master switches for gene regulation, they become the unique candidates for targeting functional hub and dynamic networks and nodes of different defence signalling pathways in plant. Of many approaches transgenic overexpression or down-regulation of TFs is widely adopted, mainly to characterize their vital role in disease resistance; however their practical utilization remains limited in breeding programmes. Alternatively, exogenous application of synthetic chemicals/biocontrol agents is also efficient to regulate their expression, but not successful in the field. Hence, the focus has now shifted towards synthetic promoters (SPs) and synthetic transcription factors (STFs) to modulate gene expression. They have greater advantages over the natural ones for their target sequence-specificity, speed, and precise activity. Therefore, manipulation of plant defence regulatory networks by utilizing SPs or STFs represents a new era for synthetically modified crops without negative aspects of the existing biotechnology. This dynamic shift in approach from conventional to modern, transgenic to non-transgenic for manipulating plant defence is discussed in this article, with the aim of their commercial application in crop improvement.