The results show that different strains have divergent activation patterns of immune genes and may adopt distinct colonization modes, which provide an important basis for selecting Agrobacterium strains for transient expression in N. benthamiana, optimizing tobacco transient expression systems, and constructing high-efficiency plant bioreactors.
Abstract
Transient plant expression, which relies on Agrobacterium carrying T-DNA with target genes infiltrated into leaves for transient nuclear expression, is crucial for gene function research and the rapid production of pharmaceutical proteins. Commonly used laboratory Agrobacterium strains differ in their genetic backgrounds and modified helper Ti plasmids, which may induce varying degrees and durations of host immune responses and transcriptional reprogramming. However, the differential responses of N. benthamiana, the most commonly used host, to these strains remain unclear. In this study, we for the first time systematically investigated the transcriptional defense responses of N. benthamiana to six common laboratory Agrobacterium strains (Agrobacterium tumefaciens C58C1, GV3101, LBA4404, AGL-1, EHA105, and the Rhizobium rhizogene strain ArA4). Transcriptome profiling of tobacco leaves was conducted at 3 and 7 dpi to clarify the conserved and divergent regulation of tobacco immune pathways and stress responses by different strains. Additionally, we selected genes significantly upregulated in all strain-infiltrated groups and verified three novel defence-related genes, PAR1, WRKY81, and DMR6, that negatively regulate recombinant protein expression efficiency. We also analysed the expression patterns of previously reported immune-related genes that regulate recombinant protein yields, revealing the differential regulatory characteristics of tobacco in response to infiltration by different Agrobacterium strains. The results show that different strains have divergent activation patterns of immune genes and may adopt distinct colonization modes. We provide an important basis for selecting Agrobacterium strains for transient expression in N. benthamiana, optimizing tobacco transient expression systems, and constructing high-efficiency plant bioreactors.
Bacterial leaf streak caused by Xanthomonas translucens threatens cereal production, however, the temporal coordination of host transcriptional responses during resistant and susceptible interactions in polyploid crops remains partially understood. Here, we used time-resolved transcriptomics to characterize responses of synthetic hexaploid triticale to two X. translucens pv. undulosa strains that produce contrasting disease outcomes. The resistant interaction with non-virulent LB10 showed a strong early transcriptional response that subsequently declined, whereas responses to the virulent strain P3 progressively intensified as water-soaking symptoms developed. Analysis of syntenic A-, B-, and R-subgenome homoeologs revealed extensive regulatory asymmetry, with R-subgenome homoeologs disproportionately represented among transcriptionally suppressed genes. Despite their conserved coding sequences, homoeologs often showed divergent transcriptional responses during infection, whereas greater similarity in upstream regulatory regions was associated with more coordinated responsive trajectories. We next examined pathogen-mediated transcriptional regulation through transcription activator-like (TAL) effectors. Among eight TAL effector templates identified in LB10 and P3, TAL5-associated predicted targets showed the strongest preferential induction during P3 infection. Disruption of TAL5 in P3 predominantly reduced host gene expression, including genes involved in immune signaling, cell wall-associated defense and photosynthetic function, accompanied by reduced maximum photosystem II quantum efficiency at 72 h post-inoculation. Together, our results show that bacterial leaf streak outcomes are shaped by temporally distinct host responses and pathogen effector-associated transcriptional reprogramming, providing insight into the dynamic regulation underlying cereal-Xanthomonas interactions.
Fahad Hasan, Fazal Manan, Edward Cedrick J. Fernandez et al.· bioRxiv· 0 citations
Wild and cultivated rice accessions differ in their interaction with beneficial bacterial endophytes at the transcriptional level, indicating that microbiome-associated traits altered during domestication could be exploited for sustainable rice breeding.
Francesca A. Vaccaro, Maria Laura Amenta, Iacopo Passeri et al.· Plant Cell Reports· 0 citations
Herbaspirillum seropedicae strain HS09, previously isolated from commercial rice (Oryza sativa) and identified by molecular analysis, has shown biocontrol potential against Burkholderia glumae under greenhouse conditions. However, the molecular mechanisms by which HS09 induces systemic resistance against B. glumae in rice remain poorly understood. In this study, we investigated the molecular basis of plant growth-promoting bacteria-mediated systemic resistance against B. glumae in rice through transcriptomic analysis. Four treatments were evaluated: an untreated control, a treatment inoculated with the endophyte HS09, a treatment inoculated with the pathogen B. glumae, and an inducer treatment consisting of HS09 inoculation followed by B. glumae challenge. For the experiment, 90 seeds were used per treatment and randomly distributed under controlled greenhouse conditions. The results showed that HS09 activates key defense-related signaling pathways, particularly those mediated by jasmonic acid (JAMyb and MYC2) and ethylene (EIN3, EILs, and ERF transcription factors). In addition, Rboh and CaMCML, genes associated with calcium-dependent signaling and the hypersensitive response (HR), were upregulated, indicating the involvement of Ca²⁺-mediated defense activation. Enrichment analyses also revealed induction of the phenylpropanoid biosynthesis pathway, promoting the production of antimicrobial secondary metabolites such as isoflavones. Notably, 404 differentially expressed genes were uniquely identified in the inducer treatment, supporting the role of HS09 in priming multiple molecular pathways involved in pathogen defense. These findings highlight the potential of H. seropedicae HS09 as a sustainable biocontrol agent against B. glumae and support its integration into crop protection programs and policies aimed at reducing dependence on chemical pesticides and promoting environmentally friendly disease management strategies in rice production systems.
Zafiro Barraza Román, Héctor Alejandro Rodríguez Cabal, Zulma Isabel Monsalve F et al.· Journal of plant diseases an...· 0 citations
StERF87 directly activates StPR1a via GCC-box binding and integrates SA/ET signaling to enhance bacterial wilt resistance. Potato (Solanum tuberosum) is an important food crop worldwide, yet its yield is severely constrained by bacterial wilt caused by Ralstonia solanacearum. We used RNA-Seq to study gene expression in ‘Z1076-1’ at 0, 1, and 2 days post-inoculation (dpi) with R. solanacearum (10⁶ CFU mL⁻1). We identified 6663 differentially expressed genes at 1 dpi and 7390 at 2 dpi. Calcium signaling and MAPK cascade genes were upregulated at 1 dpi. PR protein and ROS-related genes showed stronger induction at 2 dpi. The ethylene-responsive transcription factor StERF87 was continuously upregulated. Its expression increased 4.7-fold at 2 dpi, with FPKM values over 100. We selected this gene for functional analysis. Transgenic potato plants overexpressing StERF87 showed lower disease severity and reduced bacterial growth in both whole plants and tuber slices. StERF87 is a transcriptional activator that directly binds the GCC-box in the StPR1a promoter to activate its transcription. After R. solanacearum inoculation, StERF87 overexpression also increased PR1b1 expression, elevated salicylic acid and ethylene levels, reduced jasmonic acid accumulation, and altered the activities of ROS-scavenging enzymes including SOD, POD, and CAT. These results show that StERF87 regulates potato defense against R. solanacearum and may be useful for breeding bacterial wilt-resistant varieties.
Ru Yu, Min Gao, Lin Cai et al.· Plant Cell Reports· 0 citations
Assays demonstrated that SlSN2 overexpression suppressed ToMMV accumulation and infection, likely via enhanced lignin biosynthesis, suggesting a potential role for SlSN2 in contributing to ToMMV resistance, independent of the known Tm‑2² pathway.
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
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