Modulating the Expression of Transcription Factors: An Attractive Strategy for Raising Abiotic Stress Tolerant Plants

Plants, being sessile, are strongly influenced by abiotic stress such as high salt, drought, high temperature and freezing. These factors cause metabolic toxicity, membrane disorganization, closure of stomata, decreased photosynthetic activity, generation of reactive oxygen species (ROS) and altered nutrient acquisition. In order to meet the increasing demands for plant-based agricultural commodities, it would be imperative to enhance productivity of crop plants. It is well established that tolerance to abiotic stresses is mediated by a number of biochemical reactions and physiological processes, which essentially means that it is a ‘multigenic’ trait. A large number of stress related genes are expressed in an ‘orchestrated manner’ to bring about this stress response. For this ‘stress-responsive’ unique gene expression network to accrue, transcription factors play a very crucial role. Improvement in stress tolerance through engineering of transcription factors genes is emerging as an attractive strategy in recent years. The global expression analyses have also uncovered hundreds of genes encoding transcription factors that are differentially expressed under environmental stresses, thus implying that various transcriptional regulatory mechanisms are involved. Transcription factors often comprise families of related proteins that share a homologous DNA binding domain such as ERF, bZIP, MYC, MYB, NAC and WRKY binding transcription factors. There are several reports where increased tolerance has been achieved through the overexpression of selected transcription factor(s). The manipulation of a transcription factor can control a broad range of downstream events; therefore can combat abiotic stress efficiently. This review presents a brief description of important transgenic studies which have been attempted with a view to understand the role of various transcription factors towards abiotic stress tolerance in plants. _____________________________________________________________________________________________________________