Aug 2026· Journal of Invertebrate Pathology· Vol 219, pp.
108716
· 0 citations· 54 references
Medicine
TL;DR
Six subclass III C6 transcription factors with unique Zn(II)2Cys6 binuclear cluster DNA-binding DNA-binding domain not locating at N-terminus are underexplored in Beauveria bassiana and a significance of host immune suppression for the insecticidal activity of B. bassiana is unveiled.
Abstract
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.
TF1-TF6 play essential roles in the positive regulation of insect-pathogenic lifecycle and serve as negative regulators of submerged blastospore production in vitro in B. bassiana.
Jian-Ru Feng, Min Li, Shenghua Ying et al.· Pest Management Science· 0 citations
It is demonstrated that MrFTRP1 exerts a dual-regulatory functioning as a positive regulator of conidiation and pathogenesis but a negative regulator of environmental stress tolerance, which expands the understanding of the regulatory diversity within the C6 TF family and identifies him as a promising target for the genetic improvement of mycoinsecticides.
Chentian Jiang, Hao Wu, You-Gui Tong et al.· Journal of Invertebrate Path...· 0 citations
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.
S. Morikawa, Leon Lenzo, Keshara Colomba Thanthrige et al.· bioRxiv· 0 citations
The Arabidopsis HD-Zip IV transcription factor GLABRA2 (GL2) displays dual regulatory capabilities, as an activator and repressor of genes that mediate cell-type differentiation of the epidermis. GL2 binds L1 box elements in the promoters of its target genes; however, the mechanisms by which it controls gene expression remain elusive. GL2 contains two putative ethylene-responsive element-binding factor-associated amphiphilic repression (EAR) motifs proximal to its N– and C-termini. The N-terminal EAR motif is highly conserved among GL2 orthologs that form a distinct clade of HD-Zip IV transcription factors in monocots and dicots. We demonstrate that deletion or Ala substitution of this N-terminal EAR motif results in a partial loss-of-function phenotypes in trichomes, non-hair root cells, and seed coat mucilage. In contrast, mutations affecting the C-terminal EAR motif display improper nuclear localization, likely due to protein misfolding. Yeast two-hybrid and in planta co-immunoprecipitation assays show that GL2 selectively interacts with the TOPLESS (TPL) and TPL-RELATED (TPR) corepressors via its N-terminal EAR motif. Fusion of the SUPERMAN REPRESSIVE DOMAIN X (SRDX) with the gl2 N-terminal EAR motif mutant (gl2EAR-N) rescues the epidermal defects of gl2 mutants. Transcriptome analysis of mutant and wild-type seedling roots further confirms the role of the GL2 N-terminal EAR motif in tuning gene expression. Our findings support a model whereby GL2 recruits TPL/TPR corepressors via its EAR motif to sequester histone-modifying proteins, resulting in chromatin remodeling required for epidermal development.
Bilal Ahmad, Aytug Ulutas, Ayianna K. Bailey et al.· bioRxiv· 0 citations
Sugarcane smut, caused by Sporisorium scitamineum, is one of the most devastating diseases of sugarcane worldwide, leading to severe yield losses and long-term agricultural impacts. Integral membrane proteins are essential components of plasma membranes, playing critical roles in molecular transport, signal transduction, pathogenesis, and defense. However, their contributions to sexual mating and pathogenicity in smut fungi remain largely unknown. In this study, we sought to characterize two novel integral membrane proteins—regulation of whip and teliospore development 1 (RWTD1) and pheromone-regulated multispanning membrane protein (PRM1)—in S. scitamineum. The RWTD1 protein, which contains four transmembrane domains, showed mating-specific upregulation and localized to discrete puncta in the cytoplasm near the cell membrane. The deletion of RWTD1 in Mat-1 haploids abolished filamentous growth after sexual mating, whereas its deletion in Mat-2 haploids resulted in reduced filamentation. Transcriptome profiling revealed that, relative to the wild type, genes encoding several integral and intrinsic membrane components were differentially expressed in RWTD1 mutants, including PRM1 and DIK6, which encode putative four- and seven-transmembrane domain proteins, respectively. Deleting PRM1 recapitulated the mating defects observed in the ΔRWTD1 mutants. While RWTD1, PRM1, and DIK6 contributed to virulence, RWTD1 also functioned in symptom development and teliospore formation. Overall, our work demonstrated that the transmembrane proteins RWTD1, PRM1, and DIK6 are important contributors to virulence and sexual mating in the sugarcane smut fungus.
Shan Lu, Shaofeng Tan, Mi Liang et al.· Phytopathology Research· 0 citations
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.
