The infection by a single-stranded DNA virus, Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1), causes hypovirulence, a reduced growth rate, and other colony morphological changes in its host Sclerotinia sclerotiorum strain DT-8. However, the mechanisms of the decline are still unclear. Using digital RNA sequencing, a transcriptome analysis was conducted to elucidate the phenotype-related genes with expression changes in response to SsHADV-1 infection. A total of 3110 S. sclerotiorum differentially expressed genes (DEGs) were detected during SsHADV-1 infection, 1741 of which were up-regulated, and 1369 were down-regulated. The identified DEGs were involved in several important pathways. DNA replication, DNA damage response, carbohydrate and lipid metabolism, ribosomal assembly, and translation were the affected categories in S. sclerotiorum upon SsHADV-1 infection. Moreover, the infection of SsHADV-1 also suppressed the expression of antiviral RNA silencing and virulence factor genes. These results provide further detailed insights into the effects of SsHADV-1 infection on the whole genome transcription in S. sclerotiorum.

The cuticle is the outermost layer of plant aerial tissue that interacts with the environment and protects plants against water loss and various biotic and abiotic stresses. ADP ribosylation factor guanine nucleotide exchange factor proteins (ARF-GEFs) are key components of the vesicle trafficking system. Our study discovers that AtMIN7, an Arabidopsis ARF-GEF, is critical for cuticle formation and related leaf surface defense against the bacterial pathogen Pseudomonas syringae pathovar tomato (Pto). Our transmission electron microscopy and scanning electron microscopy studies indicate that the atmin7 mutant leaves have a thinner cuticular layer, defective stomata structure, and impaired cuticle ledge of stomata compared to the leaves of wild type plants. GC–MS analysis further revealed that the amount of cutin monomers was significantly reduced in atmin7 mutant plants. Furthermore, the exogenous application of either of three plant hormones—salicylic acid, jasmonic acid, or abscisic acid—enhanced the cuticle formation in atmin7 mutant leaves and the related defense responses to the bacterial Pto infection. Thus, transport of cutin-related components by AtMIN7 may contribute to its impact on cuticle formation and related defense function.

Plants evolve a prompt and robust immune system to defend themselves against pathogen infections. Pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) is the first battle layer activated upon the PAMP’s perception, which leads to multiple defense responses. The plasma membrane (PM) H⁺-ATPases are the primary ion pumps to create and maintain the cellular membrane potential that is critical for various essential biological processes, including plant growth, development, and defense. This study discovered that the PM H⁺-ATPase AHA5 is negatively involved in Arabidopsis PTI against the virulent pathogen Pseudomonas syringae pvr. tomato (Pto) DC3000 infection. The aha5 mutant plants caused the reduced stomata opening upon the Pto infection, which was associated with the salicylic acid (SA) pathway. In addition, the aha5 mutant plants caused the increased levels of callose deposition, defense-related gene expression, and SA accumulation. Our results also indicate that the PM H⁺-ATPase activity of AHA5 probably mediates the coupling of H₂O₂ generation and the apoplast alkalization in PTI responses. Moreover, AHA5 was found to interact with a vital defense regulator, RPM1-interacting protein 4 (RIN4), in vitro and in vivo, which might also be critical for its function in PTI. In summary, our studies show that AHA5 functions as a novel and critical component that is negatively involved in PTI by coordinating different defense responses during the Arabidopsis–Pto DC3000 interaction.

We report here the genome sequence of Bacillus sp. RRD69, a plant-growth-promoting bacterial endophyte isolated from switchgrass plants grown on a reclaimed coal-mining site in Kentucky. RRD69 is predicted to contain 3,758 protein-coding genes, with a genome size of 3.715 Mbp and a 41.41% GC content. [ ] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Copper (Cu) is an essential micronutrient that serves as a cofactor for redox enzymes but becomes toxic when unregulated. In bacteria, while Cu efflux systems are well characterized, mechanisms of Cu import remain poorly understood. Here, we characterize the major facilitator superfamily transporter CuiT (STM1486) as a key Cu importer in Salmonella enterica. Comparative genomics revealed that cuiT is evolutionarily conserved across Enterobacteriaceae, and structural modeling predicts a 12-transmembrane-helix architecture with conserved His, Met, and Cys residues suitable for Cu⁺ coordination. Functional analyses demonstrated that deletion of cuiT reduces intracellular Cu accumulation, slows Cu uptake kinetics, and diminishes expression of Cu-responsive genes, including copA, cueP, cueO, and golB. Conversely, overexpression of CuiT increases intracellular Cu but sensitizes cells to Cu stress, highlighting the need for tight regulation. Kinetic modeling indicates that CuiT mediates rapid Cu import, supporting larger intracellular Cu pools compared to Pseudomonas influx transporters. These findings position CuiT as a central component of the Salmonella Cu homeostasis network, linking Cu import to transcriptional regulation, redox balance, and stress adaptation. Our work provides mechanistic insights into bacterial Cu acquisition and suggests CuiT and associated pathways as potential targets for antimicrobial strategies.

The intracellular environment Salmonella confronts during infection is characterized by multiple redox stressors including reactive oxygen species (ROS) and copper (Cu) ions. Under these conditions, alternative systems of thiol oxidoreductases such as the Cu induced Scs system are required to protect and repair periplasmic proteins. The scsABCD operon encodes three Dsb-like enzymes, ScsB, ScsC, and ScsD, and an accessory protein, ScsA. These proteins are required both for Cu resistance and H₂O₂ tolerance. ScsB and ScsC function analogously to the canonical DsbD/DsbC redox pair of thiol oxidoreductases. The absence of ScsC was shown to affect the folding/activity of periplasmic proteins involved in amino acid transport and redox homeostasis. Here, we focus in ScsD, the least characterized member of this system. Upon Cu-induced expression, ScsD localizes to the inner membrane, enabling its predicted C-terminal Dsb-like domain to be exposed to the periplasm. Functional analysis indicates that ScsD exists in a reduced state in the Salmonella envelope and serves as a redox partner of ScsB. ScsD exhibits in vivo disulfide reductase activity and restores a deficient disulfide reduction pathway in Salmonella . Similar to ScsC and ScsB, ScsD binds Cu(I) via the Cys residues of its Dsb-like domain; however, this metal interaction appears to lack relevance in Cu detoxification as no impact on intracellular Cu levels was observed. Our results define ScsD as a specialized membrane-bound thiol-disulfide reductase in the Salmonella envelope and highlight the versatility of the Scs system in maintaining periplasmic proteostasis when canonical pathways are compromised by host-imposed Cu stress. Importance: Copper is a key component of the innate immune system, serving as a primary defense against pathogens like Salmonella . Copper overload targets the bacterial envelope, specifically attacking protein sulfhydryl groups. This causes protein misfolding and inactivation, disrupting essential processes like metabolism, transport and virulence. To survive this stress and restore thiol homeostasis, Salmonella utilizes the scsABCD operon. While the ScsB-ScsC redox pair is well-documented and some protein substrates identified, the role of ScsD remains undefined. This work characterizes ScsD as an inner-membrane-anchored thiol reductase and a new redox partner for ScsB. The ScsD/ScsB pair expands the bacterium’s protein quality control capacity, allowing Salmonella to maintain envelope homeostasis within the hostile, copper-rich environment of the host.