Phenotypic Variation of Peanut Smut (Thecaphora frezii) Incidence and Severity in the U.S. Peanut Mini-Core Collection

Peanut smut is an emergent soilborne disease of peanut in South America that has significantly impacted the commercial peanut industry in Argentina. In response, plant breeders are in need of information about potential sources of smut resistance in cultivated germplasm for the rapid development of resistant cultivars. Available U.S. peanut mini-core accessions were evaluated under naturally-infested soil conditions in 2016-2019 near General Cabrera, Córdoba, Argentina, in addition to three susceptible breeding lines and four local commercial controls. Over three years, 18 mini-core accessions and two germplasm collection accessions exhibited no smut incidence in a 100-pod sample. Of those, 12 mini-core accessions and one germplasm collection accession (PI 153323) exhibited no smut incidence when all available pods were opened and examined in the 2016-2017 and 2017-2018 crop years. These 13 accessions were collected from a variety of origins across the Americas, Africa, and Asia; only three were collected from origins in South America. These results suggest that resistance mechanisms may be well-conserved across various groups within Arachis hypogaea L. The 13 identified accessions appear to be sources of resistance to peanut smut in A. hypogaea and would likely be good parent material for the development of new, resistant commercial peanut cultivars.