Association of tomato leaf curl New Delhi virus with seed and pollen
The seed transmissibility of begomoviruses is debated. Recent research confirmed the association of tomato leaf curl New Delhi virus (Begomovirus, ToLCNDV – EPPO A2 List) with seed and pollen. Transmission of ToLCNDV via seed had already been shown in courgette (Cucurbita pepo) (EPPO RS 2020/235) and in chayote (Sechium edule).
Studies conducted by Chang et al. (2023) showed that cucumber plants (Cucumis sativus) inoculated with ToLCNDV can produce infected seed (virus present in the seed coat) and those seeds will result in infected young plants, with an infection rate of 79%. ToLCNDV was also detected in pollen of infected plants, and pollen-mediated transmission tests (infected pollen on healthy plants), resulted in ToLCNDV-infected fruits. Similar results were obtained with tomato leaf curl Taiwan virus (ToLCTV) and tomato yellow leaf curl Thailand virus (TYLCTHV) in tomato (Solanum lycopersicum). This is the first report of pollen-mediated transmission of begomoviruses.
Another study by Fortes et al. (2023) on ToLCNDV on melon (Cucumis melo) showed that the virus was present in seed (seed cotyledons and embryo) at low levels. Treatment with a chemical disinfectant significantly reduced the detectable virus associated with melon seeds. No infected plants were obtained from infected seed.
Sources
Chang HH, Gustian D, Chang CJ, Jan FJ (2023) Seed and pollen transmission of tomato leaf curl New Delhi virus, tomato leaf curl Taiwan virus, and tomato yellow leaf curl Thailand virus in cucumbers and tomatoes. Plant Disease 107(7), 2002-2008. https://doi.org/10.1094/PDIS-09-22-2164-RE
Fortes IM, Pérez-Padilla V, Romero-Rodríguez B, Fernández-Muñoz R, Moyano C, Castillo AG, De León L, Moriones E (2023) Begomovirus tomato leaf curl New Delhi virus is seedborne but not seed transmitted in melon. Plant Disease 107(2), 473-479. https://apsjournals.apsnet.org/doi/10.1094/PDIS-09-21-1930-RE