Transcription Factors Interact with ABA through Gene Expression and Signaling Pathways to Mitigate Drought and Salinity Stress

Abstract

Among abiotic stressors, drought and salinity seriously affect crop growth worldwide. In plants, research has aimed to increase stress-responsive protein synthesis upstream or downstream of the various transcription factors (TFs) that alleviate drought and salinity stress. TFs play diverse roles in controlling gene expression in plants, which is necessary to regulate biological processes, such as development and environmental stress responses. In general, plant responses to different stress conditions may be either abscisic acid (ABA)-dependent or ABA-independent. A detailed understanding of how TF pathways and ABA interact to cause stress responses is essential to improve tolerance to drought and salinity stress. Despite previous progress, more active approaches based on TFs are the current focus. Therefore, the present review emphasizes the recent advancements in complex cascades of gene expression during drought and salinity responses, especially identifying the specificity and crosstalk in ABA-dependent and -independent signaling pathways. This review also highlights the transcriptional regulation of gene expression governed by various key TF pathways, including AP2/ERF, bHLH, bZIP, DREB, GATA, HD-Zip, Homeo-box, MADS-box, MYB, NAC, Tri-helix, WHIRLY, WOX, WRKY, YABBY, and zinc finger, operating in ABA-dependent and -independent signaling pathways.

Keywords: ABA; drought; genetic engineering; pathways; salinity; transcription factors.

Figure 1

Schematic diagram of TFs as key components in transcriptional regulatory networks during drought and salinity stress-signaling pathways in different crops/plants. A diagrammatic representation of gene expression and drought and salinity stress signal perception in plants via ABA-independent and ABA-dependent pathways (modified from Khan et al. [34]).

Figure 2

Genes and signaling pathways that regulate drought stress tolerance. These pathways include the AP2/ERF, bHLH, bZIP, HD-Zip, MADS-box, MYB, NAC, WHIRLY, WRKY, and zinc finger. These regulators control drought stress tolerance through ABA-independent and -induced pathways, which play an essential role in ROS-scavenging pathways. They are positive regulators in the BR pathway, enable wax biosynthesis and stomatal development, and alter chlorophyll, MDA, POD, SOD, and CAT content. Different text colors represent different transcription factors.

Figure 3

Genes and signaling pathways that regulate salinity stress tolerance. These pathways include the bHLH, HD-Zip, MADS-box, MYB, WRKY, YABBY, and zinc finger. These regulators control salinity stress tolerance through ABA-independent, -responsive, and -mediated pathways, among others, playing an essential role in ROS, chlorophyll content, MDA, POD, SOD, CAT, UV radiation, and proline content. Different text colors represent different transcription factors.

Figure 4

Genes and signaling pathways that regulate drought and salinity stress tolerance. These pathways include the AP2/ERF, bHLH, bZIP, DREB, HD-Zip, Homeo-box, MADS-box, MYB, NAC, Tri-helix, WOX, WHIRLY, WRKY, YABBY, and zinc finger. These regulators control drought and salinity stress tolerance through ABA-dependent, -independent, -responsive, -inducible, and -sensitivity pathways, among others, which play an essential role in photosynthesis, the cell cycle, stomatal development, and ROS, chlorophyll, MDA, POD, SOD, CAT, starch, and proline content. Different text colors represent different transcription factors.

Figure 5

Genetic regulatory network constructed for drought and salinity tolerance genes. The figure shows different interactions, such as gene neighborhood, fusions, co-occurrence, text mining, co-expression, and protein homology. For example, green represents the gene neighborhood, red represents gene fusion, blue represents gene co-occurrence, yellow represents text mining, and black represents co-expression.