Enhancing abiotic stress tolerance in plants by modulating properties of stress responsive transcription factors

Abstract

Drought, heat and other abiotic stresses negatively impact growth, development, yield and seed quality of plants. The perception of stress and later adaptation to it occurs via signal transduction pathways that regulate expression of stress-responsive genes. Products of these genes include proteins that are directly involved in plant protection and those that fulfill regulatory function. The latter group includes transcription factors (TFs) and other transcription-related proteins that are investigated using the tools of forward and reverse genetics. Genomics analyses also revealed the importance of other proteins such as protein kinases and phosphatases, enzymes involved in metabolism of phospholipids, signalling molecules, etc. Once the stress response pathways are described, the role of key players in these pathways can be optimised through allele mining, selection and genetic engineering. These approaches offer alternatives to classical breeding and marker-assisted selection. During plant responses to drought, a set of basic leucine zipper (bZIP), homeodomain-leucine zipper (HD-Zip) and WRKY TFs are transcriptionally or post-translationally activated via abscisic acid (ABA)-dependent signal transduction pathways. Despite a surge of data on the significance of plant bZIP, HD-Zip and WRKY TFs in the regulation of drought responses, the three-dimensional (3D) structures of these classes of TFs have been poorly defined. This structural information can be used for rational design of variant TFs that can help in understanding their oligomerisation and post-translational modification patterns, as well as their abilities to recognise target DNA sequences. In turn, this knowledge would permit the commercial application of genetically engineered TFs in agricultural biotechnology, by expression of TF variants and using the wild-type or modified promoter regions of stress-responsive genes. To this end, the aim of this review is to discuss strategies for improving tolerance of cereals to drought and other environmental stresses using molecular variants of the abiotic stress responsive TFs.