Variability in Field Response of Peanut Genotypes from the U.S. and China to Tomato Spotted Wilt Virus and Leaf Spots

Abstract

Abstract Tomato spotted wilt, caused by Tomato spotted wilt virus (TSWV) and transmitted by thrips, and early leaf spot and late leaf spot are among the most important diseases of peanut in the southeastern United States. The objective of this study was to compare field susceptibility of diverse peanut lines to TSWV and leaf spot pathogens for selection of lines for mapping population development. In field trials in 2007 and 2008, 22 genotypes were evaluated for reactions to TSWV and leaf spots. Early leaf spot was the predominate pathogen in both years. There was a near-continuous range of spotted wilt from 18% to 79% for the total incidence rating with any symptoms caused by TSWV. In general, NC94022, ‘Georganic’, C689-6-2, ‘Georgia-01R’, C724-19-25, TifGP-1, C11-154-61, C12-3-114-58, and ‘Tifguard’ were among the most resistant genotypes to TSWV, whereas GT-C20, GT-C9 and PE-2 were the most susceptible. Final percentage of defoliation by leaf spots ranged from 10% to 97% for both years. Genotypes C689-2, Georgia-01R, C12-3-114-58, C11-154-61, Tifguard and Georganic showed resistance to leaf spots, whereas ‘NC-6’, ‘Spancross’, GT-C9, GT-C20 and PE-2 were susceptible to leaf spots. There were 3 cultivars and 3 breeding lines classified as resistant to both TSWV and leaf spots; and there were 3 genotypes from China susceptible to both TSWV and leaf spots. These phenotypic disease reaction data can be used in conjunction with genetic characterization of these genotypes for development of recombinant inbred line populations in efforts to develop markers for resistance to TSWV and leaf spots.