Transcription Factors in Abiotic Stress Responses: Their Potentials in Crop Improvement

Abiotic stresses, especially drought, high salinity, flooding, and extreme temperatures, have become a big concern due to their high frequency of occurrence and usually beyond human control capacity, as well as their severe impacts on agricultural crop productivities. Under the pressures of climate change and reduction in total cultivated land worldwide for other purposes, sustaining food security to feed an increasing human population while coping with these environmental constraints is a greater challenge than ever. Generating new varieties with better traits based on gene exchange from available sources via conventional breeding methods currently no longer provides an adequate solution in coping with abiotic stresses. Therefore, another research theme attracting the scientists over the past 20 years has been to elucidate molecular mechanisms that the plants employ to defend and adapt to stress conditions. The final aims are to identify and characterize the function of important genes involved in plant responses to stress that can be used for genetic manipulation. Thanks to advances in molecular biotechnology, including gene transfer techniques such as particle bombardment, microinjection, and Agrobacterium-mediated transformation, new varieties with better stress tolerance and yield production could be made by this strategy; thus, in combination with traditional approaches, development of new lines with improved traits has become more practical. According to our current knowledge, transcription factors (TFs) have been recognized to play essential roles in regulating plant responses against adverse abiotic factors. Many TFs belonging to families AP2/EREBP, bZIP, MYB, WRKY, and NAC have been reported to participate in plant responses to various stressors. A number of TFs whose encoding genes are appropriately altered in expression level have shown enhanced tolerance capacity toward drought, salt, and suboptimal temperatures in transgenic model and crop plants. In this chapter, we summarize our current understanding about TF activities in plants under adverse stress conditions and their use in crop improvement.