Characterization of a Small Cysteine-Rich Secreted Effector, TcSCP_9014, in Tilletia controversa.

Tilletia controversa J. G. Kühn is the causal agent of wheat dwarf bunt (DB), a destructive disease causing tremendous economic losses. Small cysteine-rich secreted proteins (SCPs) of plant fungi are crucial in modulating host immunity and promoting infection. Little is known about the virulence effectors of T. controversa. Here, we characterized TcSCP_9014, a novel effector of SCPs, in T. controversa which suppressed programmed cell death triggered by BAX without relying on its signal peptide (SP). The SP in the N-terminus of TcSCP_9014 was functional in the secretory process. Live-cell imaging in the epidermal cells of Nicothiana benthamiana suggested that TcSCP_9014 localized to the plasma membrane, cytoplasm, and nucleus. Furthermore, yeast cDNA library screening was performed to obtain the interacting proteins in wheat. Yeast two-hybrid and BiFC assays were applied to validate the interaction of TcSCP_9014 with TaMTAN and TaGAPDH. Our work revealed that the novel effector TcSCP_9014 is vital in modulating plant immunity, which opens up new avenues for plant-pathogen interactions in the T. controversa infection process.

Predicting nonlinear multi-pulse propagation in optical fibers via a lightweight convolutional neural network.

The nonlinear evolution of ultrashort pulses in optical fiber has broad applications, but the computational burden of convolutional numerical solutions necessitates rapid modeling methods. Here, a lightweight convolutional neural network is designed to characterize nonlinear multi-pulse propagation in highly nonlinear fiber. With the proposed network, we achieve the forward mapping of multi-pulse propagation using the initial multi-pulse temporal profile as well as the inverse mapping of the initial multi-pulse based on the propagated multi-pulse with the coexistence of group velocity dispersion and self-phase modulation. A multi-pulse comprising various Gaussian pulses in 4-level pulse amplitude modulation is utilized to simulate the evolution of a complex random multi-pulse and investigate the prediction precision of two tasks. The results obtained from the unlearned testing sets demonstrate excellent generalization and prediction performance, with a maximum absolute error of 0.026 and 0.01 in the forward and inverse mapping, respectively. The approach provides considerable potential for modeling and predicting the evolution of an arbitrary complex multi-pulse.

Characterization of Rhizosphere Microbial Communities for Disease Incidence and Optimized Concentration of Difenoconazole Fungicide for Controlling of Wheat Dwarf Bunt.

Rhizosphere soil microorganisms have great agricultural importance. To explore the relationship between rhizosphere microorganisms and the disease incidence, and to optimize the concentration of difenoconazole fungicide for the control of wheat dwarf bunt, caused by Tilletia controversa Kühn, the rhizosphere microorganisms were characterized based on sequencing methods. We found that the disease incidence correlated with the relative abundance of some microbial communities, such as Acidobacteria, Nocardioides, Roseiflexaceae, Pyrinomonadaceae, and Gemmatimonadaceae. Actinobacteria showed significant differences in the infected soils when compared to the control soils, and the relative abundance of Acidobacteria, Pyrinomonadaceae, Gemmatimonadaceae, and Saccharimonadales populations was distinctly higher in the T. controversa-inoculated group than in the control group. The members of Dehalococcoidia, Nitrosomonadaceae, and Thermomicrobiales were found only in T. controversa-inoculated soils, and these taxa may have potential effects against the pathogen and contribute to disease control of wheat dwarf bunt. In addition, for T. controversa-infected plants, the soil treated with difenoconazole showed a high relative abundance of Proteobacteria, Actinobacteria, Ascomycota, Basidiomycota, Mortierellomycota, and Olpidiomycota based on the heatmap analysis and ANOVA. Our findings suggest that the optimized concentration of fungicide (5% recommended difenoconazole) exhibits better control efficiency and constant diversity in the rhizosphere soil.

The photocatalytic antibacterial molecular mechanisms towards Pseudomonas syringae pv. tabaci by g-C3 N4 nanosheets: insights from the cytomembrane, biofilm and motility disruption.

BACKGROUND: Antibacterial photocatalytic therapy has been employed as a promising strategy to combat antibiotic-resistant bacteria in the water disinfection field, especially some non-metal inorganic nanomaterials. However, their antibacterial activities on plant phytopathogens are poorly understood. Here, the photocatalytic antibacterial mechanism of the urea-synthesized graphitic carbon nitride nanosheets (g-C3 N4 nanosheets) against Pseudomonas syringae pv. tabaci was systematically investigated in vitro and in vivo. RESULTS: The g-C3 N4 nanosheets exhibited remarkable concentration-dependent and irradiation-time-dependent antibacterial properties, and the 0.5 mg mL-1 concentration ameliorated tobacco wildfire disease in host plants. Specifically, under visible irradiation, g-C3 N4 nanosheets produced numerous reactive oxygen species (ROS), supplementing the plentiful extracellular and intracellular ROS in bacteria. After exposing light-induced g-C3 N4 nanosheets for 1 h, 500 genes were differentially expressed, according to transcriptome analyses. Notably, the expression of genes related 'antioxidant activity' and 'membrane transport' was sharply upregulated, and those related to 'bacterial chemotaxis', 'biofilm formation', 'energy metabolism' and 'cell motility' were downregulated. After exposure for over 2 h, the longer-time pressure on the target bacteria cause the decreased biofilm formation and flagellum motility, further injuring the cell membranes leading to cytoplasm leakage and damaged DNA, eventually resulting in the bacterial death. Concomitantly, the attachment of g-C3 N4 nanosheets was a synergistic physical antibacterial pathway. The infection capacity assessment also supported the earlier supposition. CONCLUSION: These results provide novel insights into the photocatalytic antibacterial mechanisms of g-C3 N4 nanosheets at the transcriptome level, which are expected to be useful for dissecting the response pathways in antibacterial activities and for improving g-C3 N4 -based photocatalysts practices in plant disease control. © 2021 Society of Chemical Industry.

Plant-derived compounds: A potential source of drugs against Tobacco mosaic virus.

Tobacco mosaic virus (TMV) is an important plant virus that led to significant losses in the crops worldwide. In this study, the antiviral activities of Ursolic Acid (UA) and 4-methoxycoumarin against TMV and their underlying mechanisms were initially investigated for the first time. The results demonstrated that the antiviral effects of UA and 4-methoxycoumarin were as effective as those of the commercial agent lentinan, in either the protective effect, inactivation effect or curative effect. In addition, both plant-derived compounds could induce the resistance responses of tobacco plants against TMV, showing increased antioxidant enzyme activities (SOD and POD) and H2O2 accumulation in tobacco leaves after treatment with UA or 4-methoxycoumarin, along with highly expressed regulatory and defence genes in the salicylic acid signaling pathway. Meanwhile, electrolyte leakage and malondialdehyde experiments indicated that these effects did not result in phytotoxicity or damage to the leaf plasma membrane of tobacco plants. Collectively, the results demonstrate that UA and 4-methoxycoumarin have potential as eco-friendly and safe strategies to control TMV in the future.

Foliar exposure of Fe3O4 nanoparticles on Nicotiana benthamiana: Evidence for nanoparticles uptake, plant growth promoter and defense response elicitor against plant virus.

Nanoparticles are recently employed as a new strategy to directly kill pathogens (e.g., bacteria and fungus) and acted as nanofertilizers. However, the influences of this foliar deposition of nanoparticles on plant physiology particularly plant immunity are poorly understood. The uptake and physiological effects of Fe3O4 nanoparticles (Fe3O4NPs), and plant resistance response against Tobacco mosaic virus (TMV) after foliar spraying were studied. Specifically, Fe3O4NPs entered leaf cells and were transported and accumulated throughout the whole Nicotiana benthamiana plant, and increased plant dry and fresh weights, activated plant antioxidants, and upregulated SA synthesis and the expression of SA-responsive PR genes (i.e., PR1 and PR2), thereby enhancing plant resistance against TMV. Conversely, the viral infection was not inhibited in the NahG transgenic plants treated by Fe3O4NPs, suggesting the involvement of salicylic acid (SA) induced by Fe3O4NPs in the production of plant resistance. Moreover, no inhibition was observed of the infection after inoculating with the pretreated TMV mixtures. Thus, the deposition of Fe3O4NPs induced the accumulation of endogenous SA, which was correlated with the plant resistance against TMV infection. Such information is vital for valuing the risk of Fe3O4NPs products and broadens the researching and applying nanoparticles in the fight against plant diseases meantime.