Dual regulatory roles of the zinc cluster transcription factor MrFTRP1 in development, stress tolerance, and virulence of Metarhizium robertsii.

A Zn(II)2Cys6 transcription factor VdRgt1 affects microsclerotia development, virulence, and glucose utilization in the smoke tree wilt fungus Verticillium dahliae

Verticillium dahliae is a soil-borne vascular pathogen with a broad host range and the ability to survive in soil for extended periods through the formation of stress-resistant microsclerotia. It poses a major challenge to disease management and frequently causes severe Verticillium wilt in smoke tree (Cotinus coggygria) in China. Zn(II)2Cys6 transcription factors (TFs) represent a major class of fungal regulators and are involved in various biological processes, including primary and secondary metabolism, stress adaptation, and pathogenesis. In this study, we found that the deletion of VdRgt1, which belongs to Zn(II)2Cys6 TF, led to abnormal hyphal morphology, reduced vegetative growth, markedly decreased conidial production, and altered timing of microsclerotia development and melanin accumulation. Additionally, the ΔVdRgt1 mutant exhibited significantly reduced virulence and impaired colonization of C. coggygria. Transcriptome analysis indicated that VdRgt1 is involved in the regulation of carbohydrate and energy metabolism. Consistently, the ΔVdRgt1 mutant exhibited reduced ATP levels, and RT-qPCR supported a role for VdRgt1 in glucose-responsive gene regulation. Collectively, these results indicate that VdRgt1 is an important regulator in V. dahliae, coordinating hyphal development, the timing of microsclerotia development and melanin accumulation, carbon and energy metabolism, stress adaptation, and virulence.

The bZIP transcription factor PnAda1 functions as a regulator of virulence, fungicide tolerance and necrotrophy in the wheat pathogen Parastagonospora nodorum

It is shown that the understudied bZIP transcription factor PnAda1 is an important downstream component of this PnPf2-regulatory network, and current understanding of the transcriptional network underlying virulence, metabolism and stress adaptation in an important fungal wheat pathogen is expanded.

The Slt2-Swi6 signaling pathway plays a pivotal role in regulating cell wall biosynthesis, secondary metabolite production, and the pathogenicity of pear fungal A. alternata

A physical interaction is identified between AaSlt2 and Swi6/RlmA, suggesting that these components are critical for cell wall synthesis, which advances the understanding of pathogenic mechanisms of A. alternata and proposes potential strategies for controlling postharvest diseases.

Differential roles of three subclass III C6 transcription factors in the insect-pathogenic lifecycle of Beauveria bassiana.

Six subclass III C6 transcription factors (TFs) with unique Zn(II)2Cys6 binuclear cluster DNA-binding (C6 or GAL4) domain not locating at N-terminus are underexplored in Beauveria bassiana, a wide-spectrum mycoinsecticide. Here, we report that three C6 TFs with the GAL4 domain locating at C-terminus (TF1), between C-terminal and central regions (TF2) and between central and N-terminal regions (TF3) are largely differentiated in function. TF1 was proven to localize in both nucleus and cytoplasm and regulate host immune repression in the course of host hemocoel colonization instead of cuticular penetration. The deletion of tf1 resulted in much greater virulence loss via normal cuticle infection (77%) than cuticle-bypassing infection (25%) for direct hemocoel colonization by intrahemocoel injection. The deletion also led to severe defects in radial growth, multiple stress tolerances, aerial conidiation, and submerged blastospore production as well as resistance to host immune defense after invasion into host hemocoel, unveiling pleiotropic effects of TF1 in the fungal lifecycle. TF3 was similar to TF1 in subcellular feature and exhibited lesser role than TF1 in mediating conidiation and blastospore production but no other role. TF2 looks like a typical subclass III C6 TF but proved functionally null perhaps due to its localization in neither nucleus nor cytoplasm under normal culture conditions. These findings add knowledge to subclass III C6 TFs and unveil a significance of host immune suppression for the insecticidal activity of B. bassiana after hyphal invasion into insect hemocoel through cuticular penetration.

Bbsmf1, an Nramp Family Transporter, Sustains Iron Homeostasis Through Cross Pathway Compensation in Beauveria bassiana

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

Cadmium (Cd) is a widespread environmental pollutant that severely threatens crop productivity and food safety. However, the regulatory mechanisms underlying Cd detoxification and tolerance in sorghum remain largely elusive. Herein, we functionally characterized SbWRKY6, a Cd‑induced WRKY transcription factor that localizes to the nucleus and functions as a transcriptional activator. Stable overexpression of SbWRKY6 significantly enhanced Cd tolerance in sorghum, as evidenced by improved growth performance, mitigated oxidative damage, and decreased Cd concentration in plant tissues, whereas silencing of SbWRKY6 resulted in a Cd-hypersensitive phenotype with exacerbated toxicity symptoms. Mechanistically, we identified SbPLAC8-17, a member of the Plant Cadmium Resistance (PCR)/PLAC8 family, as a critical downstream target of SbWRKY6. Heterologous expression of SbPLAC8-17 functionally complemented the Cd‑sensitive phenotype of the yeast mutant ∆ycf1 and reduced intracellular Cd accumulation. Further yeast one-hybrid (Y1H), electrophoretic mobility shift assay (EMSA), and dual-luciferase reporter (Dual-LUC) assays confirmed that SbWRKY6 directly binds to the SbPLAC8-17 promoter and transcriptionally activates its expression. In vivo silencing of SbPLAC8-17 significantly impaired cellular Cd²⁺ efflux and aggravated Cd toxicity in sorghum. Additionally, the rapid Cd-induced transcriptional upregulation of SbMPK3 and its direct physical interaction with SbWRKY6 suggest a potential upstream regulatory module that remains to be functionally validated. Collectively, this study elucidates a novel SbWRKY6‑SbPLAC8-17 transcriptional cascade that positively regulates Cd tolerance by facilitating Cd²⁺ efflux, providing promising genetic targets for phytoremediation and molecular breeding of safe sorghum cultivars for Cd-contaminated fields.