Submitted to: Phytopathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/15/2005
Publication Date: 8/1/2005
Citation: Rowland, D., Dorner, J.W., Sorensen, R.B., Beasley, J., Todd, J. 2005. The progression of tomato spotted wilt virus through peanut tissue types and the resultant physiological effects as related to severity of viral infection. Phytopathology. 54:431-440. Interpretive Summary: Tomato spotted wilt virus causes devastating economic losses to the peanut industry every year. It is known that the plant virus is spread through the insect thrips when they feed on the peanut plant, but relatively nothing is known about how the plant responds physiologically to the disease once infected. This study examined how the virus spreads through the plant from roots, pegs, pods and leaves, and then looked at the physiological changes occurring in relation to the severity of infection. The capacity of the plant to photosynthesize was reduced by the disease 30-50% which helps explain why there is so much yield loss due to the infection. It was determined that there may be some peanut varieties that are able to maintain higher photosynthetic levels even when they are infected and this might be a way that plants can show some resistance to the disease.
Technical Abstract: Much has been speculated about whether certain physiological characteristics in peanut varieties enable more resistant varieties to withstand tomato spotted wilt virus (TSWV) infection better than others. In order to address this question, three peanut varieties, Georgia Green, NC-V11, and ANorden, were grown using production practices that favored the development of TSWV. The progression of TSWV infection was then examined through the season using ELISA tests in different tissue types: roots, leaves, and pods. The effect of TSWV infection on physiological function at three harvests was examined. Plants were classed into three severity categories: 1) no TSWV symptoms or previous positive ELISA tests; 2) less than 50% of leaf tissue exhibiting TSWV symptoms; and 3) greater than 50% of leaf tissue symptomatic. Further, gas exchange physiology was quantified in both symptomatic and asymptomatic leaves on a single plant. TSWV showed a slow rate of infection at the beginning of the season and a greater percentage infection of the roots than in the leaves. Photosynthesis was reduced by an average of 30% at the mid-season harvest and 51% at the late season harvest as compared to non-infected plants across all three varieties. Symptomatic leaf tissue had lower photosynthetic rates than healthy leaves. There were small differences among varieties with ANorden maintaining higher average photosynthetic levels than Georgia Green and higher transpirational levels than NC-V11. The ability to maintain high assimilation physiology in the presence of the virus may help varieties withstand TSWV infection and maintain final yields.