Plant DNA polymerases α and δ mediate replication of geminiviruses

Geminiviruses are causal agents of devastating diseases in crops. Geminiviruses have circular single-stranded (ss) DNA genomes that are replicated in the nucleus of the infected plant cell through double-stranded (ds) DNA intermediates by the plant DNA replication machinery. Which host DNA polymerase mediates geminiviral multiplication, however, has so far remained elusive. Here, we show that subunits of the nuclear replicative DNA polymerases alpha and delta physically interact with the geminivirus-encoded replication enhancer protein, C3, and that these polymerases are required for viral replication. Our results suggest that, while DNA polymerase alpha is essential to generate the viral dsDNA intermediate, DNA polymerase delta mediates the synthesis of new copies of the geminiviral ssDNA genome, and that the virus-encoded C3 may act selectively, recruiting DNA polymerase delta over epsilon to favour productive replication. Geminiviruses cause substantial damage to crops worldwide. Here Wu et al. show that geminivirus replication relies upon the host DNA polymerases alpha and delta, which produce double-stranded DNA intermediates and new copies of the viral genome, respectively, and is modulated by the viral C3 protein.