Understanding Tomato Brown Rugose Fruit Virus (ToBRFV)
The Emergence of ToBRFV
The Tomato Brown Rugose Fruit Virus, commonly referred to as ToBRFV, has become a significant concern for the tomato industry. This virus made its appearance in Nouvelle-Aquitaine last spring, with an outbreak detected in a cooperative member of the Rougeline company located in Lot-et-Garonne. This isn’t the first encounter, as the department faced a similar case at the Sainte-Livrade agricultural college near Villeneuve-sur-Lot back in 2021, marking the first authenticated instance in the region.
Origin and Spread of ToBRFV
Where Does ToBRFV Come From?
Identified for the first time in Jordan and Israel between 2013 and 2014, ToBRFV later spread to Europe, appearing initially in Germany in 2018. It has since established its presence in various countries including Spain, Italy, and the Netherlands. In France, since the first confirmed case in Brittany in 2020, several outbreaks have occurred across regions such as Pays de la Loire, Nouvelle-Aquitaine, and Provence-Alpes-Côte d’Azur, although its spread remains somewhat controlled so far.
What Makes ToBRFV So Dangerous?
ToBRFV belongs to the tobamovirus family, which has been well-managed for decades thanks to breeding programs for resistant tomato varieties. Unfortunately, ToBRFV can infect these resistant varieties, undermining decades of selection efforts. The stability and resilience of this virus make it particularly concerning.
Natural Spread of ToBRFV
The virus is extremely stable and can survive on inert surfaces for extended periods without requiring a host plant. Natural transmission occurs through micro-injuries to plants, allowing the virus to enter easily. Additionally, it can spread within greenhouses through handling tools and equipment.
Environmental and Ecosystem Risks
Upon infection, ToBRFV has the potential to infect the entire plant, including the fruit. It can also contaminate the greenhouse environment, surrounding water supplies, and entryways, leading to broader ecological implications. Reservoir plants such as black nightshade may harbor the virus and subsequently infect tomatoes, contributing to the spread of the disease.
Identifying ToBRFV Symptoms
The initial symptoms of ToBRFV manifest on the leaves, characterized by mosaics, marbling, chlorosis, and necrosis on the peduncles. However, these symptoms can vary significantly across different tomato varieties.
Fruit Manifestations
In later stages, discolorations on the fruit appear, leading to the distinctive rough and brown appearance that gives the virus its name. These fruit abnormalities render the product unmarketable, making early detection and prevention crucial.
Human Health Risks
It’s important to note that plant viruses, including ToBRFV, do not pose any danger to human health.
Preventing ToBRFV Proliferation
Once a plant is infected with ToBRFV, there’s currently no cure, making preventative measures critical. In the case of an outbreak detection, strict protocols require producers to uproot infected plants and conduct thorough cleaning of greenhouse structures, plant supports, and other potential contamination sources.
Comparative Vulnerability of Cultivation Methods
ToBRFV can infect all types of tomato crops, although cultivation practices can influence the likelihood of outbreaks. For instance:
- Open-field Tomatoes: Varieties intended for storage or sauce production require less handling, potentially limiting virus spread.
- Above-ground Greenhouses: Implementing measures to regularly replace and disinfect grow beds can reduce infection risks.
Effective Strategies to Combat ToBRFV
The primary method of defending against ToBRFV is through cultivating resistant tomato varieties. Although some promising candidates are gradually making their way into the market, the capacity for viruses to mutate rapidly necessitates the development of varieties with durable resistance.
The Challenges of Virucides
At present, no effective virucides exist that sufficiently target ToBRFV. The potential impact of such treatments on human health and the environment remains a topic of concern, echoing analogous issues surrounding antibiotic use.
Virus Resistance and Premunition
Another avenue of control comparable to vaccination is a method known as premunition, which can build plant immunity against viral attacks. This research area is of immense interest in the ongoing battle against ToBRFV.
The Importance of Vigilance and Education
For stakeholders in the tomato industry including seed companies, nurseries, farmers, and agricultural researchers, the emergence of ToBRFV signifies the need for heightened vigilance. Educational outreach and ongoing research will be essential in developing new strategies to prevent and manage outbreaks effectively. Given its rapid mutation rates, future plans must consider potential variants to maintain crop health and sustainable production.
Conclusion
Understanding and addressing the Tomato Brown Rugose Fruit Virus are imperative steps in safeguarding the tomato industry from devastating losses. By staying informed and collaborating on preventive measures, stakeholders can work together to mitigate the risks posed by this emerging viral threat.