Whitefly Preference for Poinsettia Cultivars: Impact of Plant Host Traits on Whitely Development, Survival, and Fecundity
Luis Canas, Ohio State University, $18,000, 2 year project
Executive Summary
Tomato spotted wilt virus (TSWV) is the type member of the plant-infecting viruses in the genus Tospovirus of the family Bunyaviridae. Virions are 80-120 nm pleomorphic particles with surface projections composed of two viral glycoproteins G N and Gc (Figure 1).
TSWV is transmitted by at least seven species of thrips (Thysanoptera: Thripidae) in a persistent, replicative manner (16). Frankliniella occidentalis (Pergande), the Western flower thrips, is an efficient vector of TSWV and has a wide plant host range and a global distribution (7). Thrips acquire the virus as first or early second instar larvae, but adult thrips that acquire the virus are unable transmit it (10,14,18). When larvae ingest the virus, it enters the midgut epithelial cells, where it replicates and spreads to surrounding muscle cells (10,14). Eventually, TSWV infects the salivary glands, enabling adult insects to transmit the virus for the duration of their lives (15,21). The hypothesis that TSWV acquisition involves a thrips larval midgut receptor(s) that binds the virus GPs is supported by several observations. First, the TSWV GPs are necessary for thrips acquisition but not for plant infection. Serial, mechanical inoculations of TSWV between plants lead to envelope-deficient mutants that have deletions and point mutations in the sequences encoding the GPs. These mutants are no longer transmissible by thrips, but they are not compromised in their ability to infect plants (9,11).
We have demonstrated that a soluble form of the TSWV membrane surface glycoprotein GN (which we refer to as GN-S) specifically interferes with the binding of virus to the midgut of its main insect vector Frankliniella occidentalis (20). Further, we were able to show that this initial reduction in TSWV binding to thrips midguts reduced virus transmission and titer in insects. Here we propose experiments to test the concept that we can co-opt the specificity of the viral ligand and insect vector cell receptor to develop an environmentally sound and effective insect and viral disease control agent.
For further information contact Dr. Luis Canas at canas.4@osu.edu
