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Tomato Virus: “Natural” Nanoparticles and a Beneficial Bacterium Boost Plant Defences—and Yield

Plant viral infections are a growing threat to global food security and cause major agricultural losses.

Tomato Virus: “Natural” Nanoparticles and a Beneficial Bacterium Boost Plant Defences—and Yield



This study examined the antiviral effect of chitosan nanoparticles (ChNPs) biosynthesised using Bacillus subtilis (strain 1211 EMCCN) against Potato virus Y (PVY), and assessed their impact on tomato growth and yield.

Lab-characterised nanoparticles

Scanning electron microscopy (SEM) revealed crystalline aggregates on the surface of the ChNPs, while transmission electron microscopy (TEM) showed spherical nanoparticles ranging from 12 to 198 nm in size. EDX analysis confirmed the presence of carbon, oxygen, sodium, and phosphorus. Finally, FTIR spectroscopy identified functional groups typical of chitosan, including hydroxyl, carbonyl, and amine groups.

Treatments significantly reduce disease severity and viral load

To evaluate efficacy against PVY, tomato leaves were treated with ChNPs, with B. subtilis, or with a combination of both. The treated plants showed a marked reduction in disease severity and PVY concentration compared with untreated controls.

At 28 days post-inoculation, infectivity fell to:

  • 46.7% with B. subtilis alone,

  • 33.3% with ChNPs alone,

  • 20% with the combined treatment (the best-performing option).

Dramatic improvements in growth

The combined strategy also enhanced multiple growth parameters, including:

  • shoot length: +95.0%

  • root length: +47.0%

  • leaf area: +668.1%

  • plant height: +30.7%

  • shoot/root fresh weight: +370.0% / +162.9%

  • shoot/root dry weight: +562.7% / +127.7%

Antioxidants and secondary metabolites: defences are activated

Biochemical and physiological analyses showed a strong increase in many protective and metabolic compounds, especially in above-ground tissues:

  • total pigments: +268.4%

  • flavonoids: +112.2%

  • phenols: +59.4%

  • α-tocopherol: +92.1%

  • ascorbic acid: +30.1%

  • anthocyanins: +71.3%

  • antioxidant enzymes (peroxidase, catalase, polyphenol oxidase): +51.9%, +39.6%, +73.6%

  • amino acids: +119.9%

  • proline: +93.3%

  • soluble sugars: +128.0%

  • proteins: +614.0%

Yield-related components, including carotenoids and anthocyanins, also increased significantly.

Less oxidative stress, better performance

Crucially, oxidative stress markers dropped sharply in treated plants: malondialdehyde and hydrogen peroxide levels decreased by 76.8% and 72.6%, respectively, compared with infected, untreated plants.

A more eco-friendly route to virus management

Overall, the study concludes that combining ChNPs with Bacillus subtilis could offer a more environmentally friendly approach to reducing viral disease and improving yield, by stimulating the plant’s natural defence mechanisms.

 

Hortidaily