The impact of Tomato spotted wilt virus (TSWV) resistant peanut genotypes on TSWV transmission by thrips and thrips fitness

Peanut genotypes resistant to Tomato spotted wilt virus (TSWV) are vital for management of spotted wilt disease caused by TSWV in peanut in the southeastern United States. Conventional breeding programs have developed numbers of peanut genotypes with higher level of resistance to TSWV. Cultivated peanut, Arachis hypogaea, is a tetraploid species whose closest relatives are considered to be the diploid species in the same genus Arachis. A wild species Arachis diogoi possesses high level of resistance to TSWV, and it has been used for resistance source in some breeding programs. In this study, several newly released peanut genotypes (with higher level of field resistance to TSWV) and a genotype incorporating resistance genes from A. diogoi were evaluated using thrips-mediated TSWV transmission assays.  TSWV infection rates in all selected genotypes were estimated three weeks post-inoculation using DAS-ELISA. Viral load in plants following TSWV infection was also assessed using quantitative PCR. Effects of such genotypes on thrips fitness were evaluated using microcosmic Plexi-glass cages.  Results indicated that there was no significant difference in TSWV infection rates between highly resistant genotypes and susceptible check in selected  peanut varieties; however, infection rates were significantly different among selected genotypes that including A. diogoi and the one incorporating resistance genes from A. diogoi. TSWV load varied with genotypes. Particularly, genotypes with A. diogoi in their pedigree exhibited reduced virus accumulation. Significant differences have been observed in thrips fitness in regard to reproduction and development when thrips reared on different genotypes.