Rhopalosiphum padi responses to headspace volatiles from barley yellow dwarf virus-infected and non-infected wheat plants
Karla J. Medina-Ortega, firstname.lastname@example.org, Nilsa A. Bosque-Perez, email@example.com, Sanford D. Eigenbrode, firstname.lastname@example.org, Dennis J. Schotzko, email@example.com, and Hongjian Ding, firstname.lastname@example.org. University of Idaho, Department of Plant, Soil and Entomological Sciences, P.O. Box 442339, Moscow, ID
Immigration bioassays were performed to assess responses of Rhopalosiphum padi to headspace volatiles from Barley yellow dwarf virus (BYDV)-infected and non-infected wheat plants. Treatments included untransformed (Lambert) and transgenic (103.1J, which expresses the BYDV-PAV coat protein gene) genotypes infected with BYDV, non-infected, and sham-inoculated, and a paper leaf model. Sham inoculated plants were challenged with non-viruliferous aphids as a control to assess responses induced by aphid feeding. Plants were inoculated at the 2 to 3-leaf stage. Observations where taken 15 days after inoculation for every treatment. We measured immigration rates of virus-free apterae at intervals of 5 minutes for 30 minutes in darkness. Thirty aphids were placed in an arena that consisted of a 150 mm Petri dish fitted with a false floor of polyethylene screening (mesh size ca. 1 mm) on which the aphids could walk freely but could not contact the leaves, which were still attached to the plants. Aphids above or near the leaves (within 1 cm) were considered immigrants. Aphids recorded on each observation were subsequently removed from the arena. Volatiles were collected from each plant and ELISA tests were performed to determine virus titer. Immigration rates were significantly higher towards BYDV-infected Lambert plants compared to the other treatments. Aphid immigration rates did not differ among BYDV-infected 103.1J plants, and non-infected and sham inoculated plants of both genotypes. Immigration rates towards the paper leaf model differed significantly from the other treatments and were the lowest observed in the assay.