Studies on weed hosts of tomato brown rugose fruit virus
Tomato brown rugose fruit virus (Tobamovirus, ToBRFV – EPPO A2 List) was initially described in greenhouse-grown tomatoes in the Jordan Valley in 2015 (Salem et al., 2016). Since then, this virus has been detected every year in tomato-growing areas across Jordan, and these continuous outbreaks have raised concern about the possible role of weed hosts in the disease epidemiology. From February 2019 to November 2021, weeds were collected in tomato fields and glasshouses in the Jordan Valley and highlands in the main tomato-growing areas. A wide range of weed species (30 plant species corresponding to 16 families) was found in tomato crops and most collected plants were asymptomatic (with a few exceptions showing yellowing, stunting, mosaic, or mottling). Out of 258 collected samples, ToBRFV was detected (DAS-ELISA followed by mechanical inoculation to Nicotiana tabacum, D. metel, D. stramonium and confirmed by RT-PCR) in 114 samples corresponding to 12 plant species: Amaranthus retroflexus, Beta vulgaris subsp. maritima, and Chenopodium murale (Amaranthaceae); Conyza canadensis and Taraxacum officinale (Asteraceae); Malva parviflora (Malvaceae); Oxalis corniculata (Oxalidaceae); Portulaca oleracea (Portulaceae); Veronica syriaca (Scrophulariaceae); Solanum elaeagnifolium and S. nigrum (Solanaceae); and Corchorus olitorius (Tiliaceae). Plant species for which more than 50% of the collected samples were infected, included A. retroflexus, C. canadensis, T. officinale, C. murale, M. parviflora, V. syriaca, and S. nigrum.
During these studies, ripe fruits of S. nigrum were also collected from symptomatic plants for further experiments to assess the seed transmission of ToBRFV. Results showed that ToBRFV could be transmitted from contaminated seeds of S. nigrum to seedlings at a low rate (approximately 1.9%); and as a control, all seedlings originating from healthy seeds were confirmed to be virus-free by DAS-ELISA and RT-PCR.
The authors concluded that management strategies for ToBRFV in tomato crops should be reconsidered to include appropriate weed control.
Sources
Salem NM, Abumuslem M, Turina M, Samarah N, Sulaiman A, Abu-Irmaileh B, Ata Y (2022) New weed hosts for tomato brown rugose fruit virus in wild Mediterranean vegetation. Plants 11, 2287. https://doi.org/10.3390/plants11172287
Salem N, Mansour A, Ciuffo M, Falk BW, Turina M (2016) A new tobamovirus infecting tomato crops in Jordan. Archives of Virology 161(2), 503-506.