Demonstration of Insect Vector-Mediated Transfer of a Betasatellite between Two Helper Viruses

Begomoviruses, transmitted by the whitefly Bemisia tabaci, pose significant threats to global agriculture due to their severe impact on various crops. Among the satellite molecules associated with begomoviruses, betasatellites play a crucial role in enhancing disease severity and yield losses. The spread and association of these molecules with helper viruses in host plants are thus matters of concern. Here, we focus on the propagation of betasatellites and, more specifically, on their transfer between different helper viruses and hosts through vector transmission. Our results show that the cotton leaf curl Gezira betasatellite (CLCuGeB), initially acquired with its helper virus cotton leaf curl Gezira virus (CLCuGeV) from an okra plant, can be transmitted and assisted by a different helper virus, tomato yellow leaf curl virus (TYLCV), in a different host plant (tomato plant). The new association can be formed whether TYLCV and CLCuGeB encounter each other in a host plant previously infected with TYLCV or in whiteflies having acquired the different components separately. Our findings reveal two pathways by which betasatellites can be transferred between helper viruses and host plants and highlight the ability of betasatellites to spread in begomovirus-infected environments.