Biosynthesized silver nanoparticles inhibit Pseudomonas syringae pv. tabaci by directly destroying bacteria and inducing plant resistance in Nicotiana benthamiana

Abstract

Silver (Ag)-containing agents or materials are widely used today in plant protection for their antimicrobial activity. In view of the superior inhibitory ability of biosynthesized (aldehyde-modified sodium alginate based) silver nanoparticles (AgNPs) against plant pathogenic fungi in our previous research, here we explored the antagonistic effect of biosynthesized AgNPs on plant pathogenic bacteria and the underlying mechanism. We selected Pseudomonas syringae pv. tabaci, the causal agent of tobacco wildfire disease, as the target and found that 1.2 μg/mL biosynthesized AgNPs completely inhibited the growth of P. syringae pv. tabaci in vitro and in vivo by partly destroying the cell membrane structure of the pathogen, resulting in cytoplasmic leakage. Moreover, Nicotiana benthamiana treated with 1.2 μg/mL biosynthesized AgNPs exhibited a significant upregulation of nonexpressor of pathogenesis-related genes 1 (NPR1) and pathogenesis-related gene 2 (PR2), the typical markers of the salicylic acid (SA)-mediated defense system, and an increase in peroxidase (POD) and polyphenol oxidase (PPO) activities as well as the production of reactive oxygen species (ROS). Furthermore, biosynthesized AgNPs treatment increased the chlorophyll content and dry weight of N. benthamiana. Overall, we demonstrated that biosynthesized AgNPs at a low concentration have high inhibitory effect on the pathogen causing tobacco wildfire disease by destroying bacterial cell membrane and inducing defense resistance in host plant. These results lay a theoretical foundation for further application of biosynthesized AgNPs in the control of plant bacterial diseases.

Comparing the antibacterial activity of chitin nanocrystals with chitin: exploring the feasibility of chitin nanocrystals as novel pesticide nanocarriers in agriculture

“…52 At present, the primary control strategies for this pathogen rely on chemical methods, typically involving the use of bactericide to suppress its growth. 15 Although bactericide can provide short-term effectiveness in disease control, they come with certain limitations. One significant drawback is the development of bacterial resistance to chemical treatments over time.…”

“…Tabaci is significant, resulting in reduced crop quality, lower market value, and substantial yield losses 52 . At present, the primary control strategies for this pathogen rely on chemical methods, typically involving the use of bactericide to suppress its growth 15 . Although bactericide can provide short‐term effectiveness in disease control, they come with certain limitations.…”

“…Employing AgNPs on plants provides an effective means of controlling the advancement of fungal and bacterial diseases. 14,15 In more recent developments, copper nanoparticles have proven to be effective agents in inhibiting a wide range of plant pathogenic microorganisms. 16 For example, they have successfully suppressed the development of bacterial leaf blight in rice caused by X. oryzae pv.…”

“…Biological experiments demonstrated the remarkable efficacy of these AgNPs against plant fungi and bacteria. Employing AgNPs on plants provides an effective means of controlling the advancement of fungal and bacterial diseases 14,15 . In more recent developments, copper nanoparticles have proven to be effective agents in inhibiting a wide range of plant pathogenic microorganisms 16 .…”

Adapting the inoculation methods of kiwifruit canker disease to identify efficient biocontrol bacteria from branch microbiome

“…Because there is no eradication treatment, control of Psa‐induced kiwifruit canker disease is largely dependent on preventive measures, such as disinfecting agricultural tools, restricting access to orchards, monitoring the grafting process, plant elicitors, copper‐formulations, antibiotics, and bacteriophage and photodynamic therapy (Borkar & Yumlembam, 2017; CABI, 2019; Donati et al., 2014; EPPO, 2014; Monchiero et al., 2015). In addition, silver nanoparticles can directly destroy P. syringae (Jiang et al., 2022), which may also have protective effects against Psa. At present, a few biological control agents of kiwifruit canker disease have been approved in the laboratory, field or market, including Serenade Max ( Bacillus subtilis QST713), BacStar ( B. subtilis var.…”