Host Plant Resistance Against Tomato spotted wilt virus in Peanut (Arachis hypogaea) and Its Impact on Susceptibility to the Virus, Virus Population Genetics, and Vector Feeding Behavior and Survival

Abstract

Tomato spotted wilt virus (TSWV) severely affects peanut production in the southeastern United States. Breeding efforts over the last three decades resulted in the release of numerous peanut genotypes with field resistance to TSWV. The degree of field resistance in these genotypes has steadily increased over time, with recently released genotypes exhibiting a higher degree of field resistance than older genotypes. However, most new genotypes have never been evaluated in the greenhouse or laboratory against TSWV or thrips, and the mechanism of resistance is unknown. In this study, TSWV-resistant and -susceptible genotypes were subjected to TSWV mechanical inoculation. The incidence of TSWV infection was 71.7 to 87.2%. Estimation of TSWV nucleocapsid (N) gene copies did not reveal significant differences between resistant and susceptible genotypes. Parsimony and principal component analyses of N gene nucleotide sequences revealed inconsistent differences between virus isolates collected from resistant and susceptible genotypes and between old (collected in 1998) and new (2010) isolates. Amino acid sequence analyses indicated consistent differences between old and new isolates. In addition, we found evidence for overabundance of nonsynonymous substitutions. However, there was no evidence for positive selection. Purifying selection, population expansion, and differentiation seem to have influenced the TSWV populations temporally rather than positive selection induced by host resistance. Choice and no-choice tests indicated that resistant and susceptible genotypes differentially affected thrips feeding and survival. Thrips feeding and survival were suppressed on some resistant genotypes compared with susceptible genotypes. These findings reveal how TSWV resistance in peanut could influence evolution, epidemiology, and management of TSWV.

Tropical Food Legumes

“…They include breeding lines F NC 94002 and F NC 94022, which are used in generating TSWV-resistant groundnut cultivars (Culbreath & Srinivasan, 2011). Newly identified field-resistant groundnut genotypes have recently been evaluated under laboratory conditions against TSWV or thrips to understand the mechanism of resistance (Sundaraj, Srinivasan, Culbreath, Riley, & Pappu, 2014). Thrips feeding and survival were suppressed on some resistant genotypes compared with susceptible genotypes.…”

Assessing the Consequences of Microbial Infection in Field Trials: Seen, Unseen, Beneficial, Parasitic and Pathogenic

“…For systemic diseases, or diseases that invariably kill whole plants, disease incidence may be a sufficient description e.g., [18], with disease on crops or plants being reported as either present or absent. Similarly, when disease levels are low, incidence may be an adequate approximation of severity.…”

Heritability of spotted wilt resistance in a Florida‐EP™ “113”‐derived peanut (Arachis hypogaea) population

“…No single method has proven effective to control spotted wilt in peanut, but several factors affect the disease severity, including peanut cultivar, planting date, plant population density, row pattern, crop rotation, and tillage. Risk values involving these factors have been combined into an integrated disease management tool called Peanut Rx (Culbreath, Todd, & Brown, 2003;Sundaraj, Srinivasan, Culbreath, Riley, & Pappu, 2014). Within the index, the single most important factor in mitigating risk of losses from spotted wilt is cultivar resistance.…”