Pre‐infection of tomato plants carrying the Sw‐5 gene with tomato chlorosis virus did not alter infection with groundnut ringspot virus in the field

Tomato crops are affected by various viral diseases. In Brazil, the most frequent of these diseases are caused by the begomovirus tomato severe rugose virus (ToSRV), the crinivirus tomato chlorosis virus (ToCV) and orthotospoviruses, mainly groundnut ringspot virus (GRSV) and tomato chlorotic spot virus (TCSV). Mixed infections can result in synergistic interactions and, in some cases, the breakdown of resistance, as previously reported for the interaction between ToCV and tomato spotted wilt virus (TSWV) in tomato plants carrying the Sw-5 orthotospovirus-resistance gene. This study evaluated the interaction between ToCV and the orthotospoviruses GRSV, TCSV and TSWV in tomato plants carrying the Sw-5 gene, as well as the attractiveness of ToCV-infected tomato plants to thrips in the field. Greenhouse assays demonstrated that the resistance to infection with GRSV and TCSV was overcome in 17% of the tomato plants previously infected with ToCV. In contrast, ToCV-pre-infected plants remained resistant to TSWV. Under field conditions, the incidence of orthotospoviruses was low in resistant tomato cultivars, even with a high incidence of ToCV-infected tomato plants, indicating the effectiveness of the Sw-5 gene. ToCV pre-infection of tomato plants did not influence their attractiveness to thrips. In conclusion, pre-infection with ToCV did not influence the effectiveness of the Sw-5 resistance gene against GRSV under field conditions.