Identification of Germplasm Resistant to Peanut Smut

Peanut smut, caused by Thecaphora frezzii, is an emerging threat to global peanut production. Found in 100% of Argentinian peanut growing regions, smut infestation can result in substantial yield reductions. Although peanut smut has not been reported outside of South America, immediate proactive measures must be taken so that global peanut production will not be threatened. The first step in preventative breeding for resistance to peanut smut is to identify sources of resistance. Therefore, the objective of this study was to identify germplasm resistant to T. frezzii that can be used to incorporate smut resistance into cultivars optimized for U.S. peanut production areas. In this study, peanut genotypes, including accessions from the USDA germplasm collection that were purified by single-seed descent, peanut breeding lines, and U.S. cultivars, were screened for resistance. Trials were planted in test plots highly infested with T. frezzii in Córdoba Province, Argentina. For screening purposes, entries were retained for future testing if they scored 10% or less disease incidence. Among the entries tested in the 2017-2020 growing seasons, potential new sources of peanut smut resistance were noted. Eight USDA peanut mini-core accessions were identified as immune, demonstrating 0% incidence for three years. These accessions are being used to incorporate smut resistance into cultivars suitable for production in all growing regions of the U.S.