D3501: High-throughput phenotyping of resistance to aphid-vectored yellow dwarf viruses in grass seed crops

Epidemiology and management of aphid-vectored yellow dwarf viruses (YDVs) have received significant international attention in small grain crops over the past century. However, focused research regarding disease management in perennial grass seed production systems, including perennial ryegrass and tall fescue, is limited. An improved understanding of host plant resistance among current grass seed cultivars is needed to reduce the impact of the aphid-YDV virus vector complex in grass seed crops in western Oregon. The primary objective of the study was to evaluate common perennial ryegrass and tall fescue cultivars grown for seed for aphid-YDV susceptibility using greenhouse experiments and laboratory screening with computer vision. We selected the most prevalent aphid vector (bird cherry-oat aphid) and virus species (PAV) in the Willamette Valley for this study. Multiple greenhouse trials were conducted to evaluate 27 grass seed cultivars for aphid-YDV susceptibility by infesting plants with PAV aphids, non-PAV aphids and no aphids for ten days; PAV infection, plant biomass and aphid fecundity were recorded. In the laboratory, computer vision was used to evaluate aphid behavior (number of feeding probes and feeding duration) in PAV and non-PAV aphids for the 27 cultivars. Across cultivar treatments, clear trends were observed: 1) root biomass was lower in PAV+ aphid treatments than PAV- aphids and untreated control in greenhouse experiments, and 2) feeding probes were greater for PAV+ aphids than PAV- aphids (the inverse was true for feeding duration) in automated video tracking trials. Further results and analyses are in progress.