Rescue of tomato yellow leaf curl virus mutants harboring heterologous iterons through <i>in planta</i> evolution

Geminiviruses are important crop pathogens worldwide for which effective control measures are lacking due to an incomplete understanding of their evolutionary dynamics in infected plants. The current study focuses on a class of short sequence repeats in geminiviral genomic DNA, known as iterons, located immediately upstream of the viral gene encoding replication protein (Rep). Iterons are interesting because, although their positions and repeat patterns are conserved across all geminiviruses, their sequence identities are highly diverse. Our investigations revealed that, contrary to previous reports, the sequence identity of iterons is non-essential for tomato yellow leaf curl virus replication. Rather, they are repressors of replication, and this repression is overcome by their binding with cognate Rep. Future investigations will likely unveil novel targets for more effective management of crop diseases caused by geminiviruses.