Spread of Tomato Brown Rugose Fruit Virus in Sicily and Evaluation of the Spatiotemporal Dispersion in Experimental Conditions

Abstract

Tomato brown rugose fruit virus (ToBRFV) is an emerging pathogen that causes severe disease in tomato (Solanum lycopersicum L.) crops. The first ToBRFV outbreak in Italy occurred in 2018 in several Sicilian provinces, representing a serious threat for tomato production. In the present work, the spatiotemporal displacement of ToBRFV in Sicily was evaluated, analyzing a total of 590 lots of tomato seed, 982 lots of plantlets from nurseries and 100 commercial greenhouses. Furthermore, we investigated the ToBRFV spreading dynamic in a greenhouse under experimental conditions. Results showed several aspects related to ToBRFV dispersion in protected tomato crops. In detail, an important decrease of the ToBRFV-infected seed and plantlet lots was detected. Regarding the examined commercial greenhouses, ToBRFV still appears to be present in Sicily, although there has been a decrease during monitoring. In experimental conditions, it was demonstrated that the presence of few infected plants are sufficient to damage the entire crop in a short time, reaching almost 100% of infection.

Tomato Brown Rugose Fruit Virus: Seed Transmission Rate and Efficacy of Different Seed Disinfection Treatments

“…The study of the epidemiology and of the distinct mechanisms involved in the dispersion of different pathogens represents one of the most important measures for containing a possible epidemic [ 32 , 35 ] and developing efficient disease management strategies [ 35 , 36 ]. From this perspective, the plant pathogens being spread by seed are extremely important, because this allows the pathogens to move from one country or continent to another in an extremely short time [ 37 ].…”

“…ToBRFV diffusion relies on long distance dispersion through the movement of infected seeds from one country to another, and on short distance dispersion by operators, pollinating insects, and—the most important—plant-to-plant contact that represents the most dangerous aspect for ToBRFV’s rapid spread [ 32 ].…”

“…In this work we demonstrated that the transmission rate in tomato-cherry is around 2.8% to the cotyledons and 1.8% to the third true leaf. Considering ToBRFV’s high plant-to-plant transmission rate, very few infected plants are sufficient in a greenhouse to have a 100% infection rate a few months after transplant, which is enhanced by the presence of bumblebees [ 14 ] and different agronomic practices during the production cycle [ 32 ].…”

“…About 200 mg of fresh leaf tissue from an infected plant were ground in a mortar with 6 mL of phosphate buffer pH 7 (0.2 M NaH 2 PO 4 , 0.2 M Na 2 HPO 4 x 7H 2 O), distributed and rubbed on plant leaf surfaces previously sprinkled with Carborundum (320 mesh), which causes micro-lesions and facilitates the virions’ entry. The inoculated plants were grown in sterilized soil with a photoperiod of 14 h of light and an air temperature of 28/20 °C day/night in an insect-proof glasshouse [ 32 ]. Severe phytosanitary measures, isolation, insect control, and careful handling were applied to avoid the accidental virus spread.…”

Differential detection ofTomato mosaic virus(ToMV) andTomato brown rugose fruit virus(ToBRFV) using CRISPR-Cas12

“…ORF4 encodes the 17-18 kDa viral coat protein (CP) (Dawson et al1986; Goelet et al 1982). Tobamoviruses are highly infectious and transmitted by mechanical contact with working hands, tools, soil, and other infected plants (Reingold et al 2016; Tomlinson 1987; Panno et al 2020).…”