Evaluation of tomato spotted wilt virus (TSWV)-resistant and susceptible peanut genotypes by thrips-mediated TSWV transmission experiments

Thrips transmitted Tomato spotted wilt virus (TSWV) is an economically important pathogen that causes spotted wilt disease in peanut (Arachis hypogaea L.). For several decades, peanut production in the United States has been challenged by spotted wilt incidences. Planting genotypes with field resistance to TSWV is the most widely adopted management tactic. However, genetic bases and mechanisms conferring resistance to TSWV have not been identified in peanut. In this study, we investigated the effects of newly released resistant genotypes (Georganic, Georgia-06G, Tifguard, NC94022) and a susceptible genotype (Georgia Green) on tobacco thrips, Frankliniella fusca (Hinds) and TSWV. Thrips-mediated transmission demonstrated that both resistant and susceptible genotypes were susceptible to TSWV. However, estimation of TSWV titers revealed that some resistant genotypes accumulated less TSWV titers than the susceptible genotype. TSWV acquisition ability of thrips reared on different genotypes was assessed through western blotting. The results revealed that F. fusca larvae acquired TSWV from TSWV-infected leaflets of both resistant and susceptible peanut genotypes, albeit at a lower efficiency from some resistant genotypes than a susceptible genotype. These results provided no evidence of involvement of a major gene conferring resistance to TSWV and indicated that TSWV resistance in genotypes displaying field resistance could be influenced by minor genes resulting in a phenomenon similar to tolerance. Further, thrips biology studies revealed very minor differences in thrips reproduction and development between TSWV-resistant and susceptible genotypes. This suggested that TSWV-resistant genotypes have little or no thrips resistance.