PRIMASE: Durable resistance to begomoviruses

An early step of infection of begomoviruses is the conversion of the incoming single-stranded (ss) DNA of the virus into double-stranded (ds)DNA. Once there is dsDNA, the genes of the virus are transcribed, and viral progeny is created via rolling-circle-replication. These latter steps have been elucidated, but the very first step of making double-stranded DNA has remained a mystery. Very recently we discovered that PriL from the plant is required for the life cycle of begomoviruses, most likely to initiate the very first step to enable ss- to dsDNA conversion. In all living organisms including plants, PriL is an essential and very conserved gene that generates primers on ssDNA for DNA replication. Our finding of SNPs in PriL from melon leading to a loss of susceptibility to viral infections, supports the idea that PriL PRIMEs the conversion of the geminiviral ssDNA genome into dsDNA molecules, similarly as PriL does in other organisms. The replication of begomoviruses is a highly conserved process. This turns PriL into a very promising S-genes for resistance against ALL begomoviruses, irrespective of their host range. This can lead to durable resistance to begomoviruses in cucurbits, pepper, cotton, beet, grapevine, tomato, and many other crops.

In this project we will study which mutations in PriL prevent viral replication, while still supporting DNA replication of the plant. Secondly, we aim to apply this knowledge to a series of cucurbit crops and pepper, investigating natural variation of PriL and EMS mutagenized crops, for obtaining durable resistance against begomoviruses.