The transcription factor SbWRKY6 confers cadmium tolerance via activating SbPLAC8-17 expression in sorghum.

Transcription Factor TCP9 Enhances Arabidopsis Tolerance to Cadmium Toxicity via ZAT6 and ZAT10 Activation

Cadmium (Cd), a highly toxic and mobile heavy metal, has emerged as a severe environmental concern in global agroecosystems, posing a substantial threat to human health. Although prior studies have established that ZAT6 and ZAT10 positively regulate Arabidopsis tolerance to Cd toxicity, the underlying molecular mechanisms remain largely elusive. The present study provides evidence that a class I TCP transcription factor, TCP9, significantly enhances Arabidopsis tolerance to Cd toxicity through the direct activation of ZAT6 and ZAT10 expression. The real-time quantitative PCR (RT-qPCR) analysis indicates that the expression of TCP9 was induced under Cd toxicity. Meanwhile, the tcp9 mutant exhibited heightened sensitivity to Cd toxicity, accompanied by elevated Cd accumulation in both shoots and roots. Notably, the complemented lines exhibited phenotypic characteristics analogous to those observed in the wild-type (WT) plants. Further physiological and biochemical analyses revealed that, in comparison to WT, the tcp9 mutant displayed elevated hydrogen peroxide (H2O2) accumulation and reduced contents of catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD) under Cd toxicity. Furthermore, TCP9 directly interacted with the promoters of ZAT6 and ZAT10 in vitro, facilitating their transcription and consequently enhancing plant tolerance to Cd toxicity. Overall, our findings showed that TCP9 enhances Cd tolerance via modulating ZAT6 and ZAT10, thereby identifying TCP9 as a potential key target for improving plant tolerance to Cd toxicity.

The transcription factor SbbHLH168 enhances salt tolerance by coordinating ion homeostasis and lignin content in sorghum

Soil salinization is an escalating global threat to crop productivity. Here, we demonstrate that the sorghum bHLH transcription factor SbbHLH168 is a central regulator of salt-stress tolerance. SbbHLH168 is nuclear-localized, constitutively expressed in all organs and rapidly up-regulated by NaCl. Overexpression of SbbHLH168 in either Arabidopsis or sorghum conferred markedly higher biomass retention, longer roots, lower relative electrical conductivity, less accumulation of superoxide and H₂O₂, and lower Na⁺/K⁺ ratio through decreased Na⁺ accumulation under salt stress, whereas VIGS silent groups displayed the opposite phenotype. qRT-PCR and biochemical assays demonstrated that SbbHLH168 up-regulates key lignin-biosynthetic genes (SbC4H, SbF5H, SbCOMT1) and increases root lignin content under salt stress, thereby reinforcing cell-wall integrity and limiting ion leakage. Furthermore, yeast two-hybrid and BiFC assays confirmed that SbbHLH168 interacts with SbbHLH35 in the nucleus, indicating that SbbHLH168's functional activity depends on heterodimerization with SbbHLH35. Collectively, SbbHLH168 integrates ion homeostasis, ROS scavenging and lignin content to confer salt tolerance, providing a direct gene target for molecular breeding of resilient sorghum cultivars.

The gene homologous to OsCd1, designated as ABNORMAL SHOOT IN YOUTH (OsASY), functions as a cadmium influx transporter in rice.

Preliminary evidence indicates that targeted editing of OsASY offers a promising strategy to reduce grain Cd content without adversely affecting major agronomic traits or yield, highlighting its potential as a molecular target for breeding low-Cd-accumulating rice varieties.

ZmbHLH164 confers mercury tolerance in maize by modulation of mercury accumulation and ROS homeostasis.

Mercury (Hg) is a highly toxic heavy metal that poses a significant threat to crop productivity. Although bHLH transcription factors are known to regulate plant stress responses, their functions in maize (Zea mays) under Hg stress remain largely unexplored. Here, we identify ZmbHLH164, a maize bHLH gene transcriptionally induced by Hg exposure, as a key regulator of Hg tolerance. Overexpression of ZmbHLH164 significantly reduced Hg accumulation in roots and root‑to‑shoot translocation, thereby enhancing Hg tolerance in maize seedlings. Conversely, knockdown of ZmbHLH164 led to increased Hg accumulation and translocation, with a concomitant loss of tolerance. Mechanistically, using DAP‑seq in combination with yeast one‑hybrid and dual‑luciferase reporter assays, we show that ZmbHLH164 directly binds to the promoter of the catalase gene ZmCAT1 and activates its transcription. This activation enhances CAT activity, promotes H₂O₂ scavenging, and sustains reactive oxygen species (ROS) homeostasis. In parallel, DAP‑seq profiling and yeast one‑hybrid assays revealed that ZmbHLH164 also directly associates with the promoters of multiple metal transporter genes, and qRT‑PCR analysis confirmed that their expression is suppressed in ZmbHLH164‑overexpressing lines, correlating with reduced cellular Hg uptake and root‑to‑shoot translocation. Together, these findings establish that ZmbHLH164 confers Hg tolerance through a dual mechanism-activating ROS detoxification while restricting Hg transport. This regulatory module not only provides mechanistic insights into plant Hg tolerance but also highlights ZmbHLH164 as a promising target for breeding low‑Hg‑accumulating crops to enhance food and environmental safety.

NtGCN2 is associated with multilayer cadmium tolerance in tobacco via coordinated transcriptional changes in growth, antioxidant, and detoxification pathways

Cold-induced SlPAL3 confers cold tolerance in tomato through interacting with putative transcription factor SlMYB58.

Cold stress severely restricts tomato growth, yield, and geographical distribution. However, the molecular mechanisms governing phenylpropanoid-mediated cold tolerance remain incompletely understood, especially the upstream regulators of specific phenylalanine ammonia-lyase (PAL) isoforms. In this study, we functionally characterized SlPAL3 and identified its putative upstream transcriptional activator SlMYB58 in tomato. Using phylogenetic analysis, subcellular localization, and the generation of CRISPR-Cas9 knockout (CR) and overexpression (OE) transgenic lines, we demonstrated that cytoplasm-localized SlPAL3 positively regulates cold tolerance. Under 4 °C treatment, OE-SlPAL3 plants exhibited enhanced phenotypes, including significantly higher peroxidase activity (2.2~3.1-fold), proline accumulation (2.1~2.6-fold), and lignin content (1.6~2.0-fold) compared to wild-type plants. In contrast, CR lines showed severe wilting and compromised physiological responses. Notably, SlPAL3 overexpression substantially reduced the accumulation of superoxide anion and hydrogen peroxide, as visualized by NBT and DAB staining, and upregulated cold-responsive markers, including SlSGR, SlABI1, and SlSOD. Furthermore, yeast one-hybrid and dual-luciferase assays revealed that putative SlMYB58, a conserved R2R3-MYB transcription factor, directly binds to and activates the SlPAL3 promoter. Collectively, these findings establish the SlMYB58-SlPAL3 module as a novel regulatory axis that integrates transcriptional activation with phenylpropanoid metabolism under cold stress. This study provides a mechanistic framework for understanding cold-induced metabolic reprogramming in tomato and identifies a strategic genetic target for breeding cold-tolerant tomato cultivars.