Development of real-time RT-PCR assays for two viruses infecting pome fruit.

Apple stem grooving virus (ASGV) and Apple green crinkle-associated virus (AGCaV) negatively impact production, maintenance, and distribution of apples and other Malus species world-wide. Due to the increasing diversity of isolates found by high-throughput sequencing, we have developed real-time RT-qPCR assays for these two viruses. Primers and probes were designed against alignments of representative extant sequences from around the world, and reaction conditions optimized for sensitivity and specificity. Assays were validated against a panel of virus isolates, and compared to extant endpoint RT-PCR and ELISA assays. The new real-time RT-qPCR assays showed greater detection sensitivity than extant assays and were able to detect their target viruses from different host tissues.