Development of a detached leaf procedure to evaluate susceptibility to Plum pox virus infection by the green peach aphid (Myzus persicae (Sulzer)) in peach

Abstract

A method was developed to evaluate susceptibility of peach leaves to Plum pox virus (PPV) infection by aphids. We examined whether virus multiplication could be detected in aphid inoculated detached leaves and if transmission efficiency of PPV by green peach aphids to detached leaves was comparable with that of peach seedlings. Results demonstrated that transmission efficiencies of viruliferous aphids transferred to detached peach leaves subsequently maintained on an agar layer for three weeks was not significantly different from that for intact seedlings. Overlaying infected PPV plum or peach leaf segments on the healthy peach leaves with subsequent application of aphids to the infected leaf pieces provided a comparable transmission efficiency. Reduced handling of the aphids using this method minimized the possibility of damaging the aphids and facilitated higher throughput testing. Comparable infection rates were obtained for detached leaves using either 50 or 25 viruliferous aphids per leaf. Residual PPV was not detected by direct quantitative reverse transcriptase polymerase chain reaction assay (DqRT-PCR) on non-host plants probed by viruliferous aphids. The effect of short term storage temperatures pre- or post-inoculation did not significantly alter the susceptibility of peach leaves to PPV infection or the transmission rate. Application of the leaf overlay method to evaluate seasonal changes in susceptibility of peach leaves in the field is the subject of an ongoing study.