In-field capable loop-mediated isothermal amplification detection of Turnip yellows virus in plants and its principal aphid vector Myzus persicae

Widespread Turnip yellows virus (TuYV) infection causes severe seed yield and quality losses in rapeseed (Brassica napus) crops grown in broadacre agricultural systems worldwide. Current TuYV detection protocols are expensive and time consuming, and can have poor specificity and sensitivity. Typically, they are used as a diagnostic tool to test already symptomatic plants, limiting their practical value to reactive disease management. To improve diagnostic services so that they provide earlier, cheaper, faster, more specific and sensitive TuYV detection, novel and innovative protocols that utilise new technology are required. A reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed to detect TuYV in crude and total RNA extractions of leaf material and its principal aphid vector Myzus persicae. The assay was based on a set of six primers, highly sensitive and specific to TuYV, derived from a TuYV isolate originating from the south-west Australian grainbelt. TuYV was readily detected in 1 in 100 dilutions of (i) infected to uninfected leaf material, and (ii) viruliferous to non-viruliferous M. persicae. Furthermore, detection was successful in a majority of aphids stored for at least 8 weeks in various trapping and storage substances, including 30% ethylene glycol, sticky trap glue and 70% ethanol. This RT-LAMP assay protocol enables quicker and cheaper diagnosis for TuYV than currently adopted laboratory-based diagnostic techniques. Ultimately, it has the potential for earlier in-field TuYV detection in combination with aphid trapping surveillance programs.