Characterization of peanut lines with interspecific introgressions conferring late leaf spot resistance

Late leaf spot (LLS) disease caused by Nothopassalora personata (Berk. & M.A. Curtis) U. Braun, C. Nakash, Videira & Crous is prevalent among pathogens encountered in peanut (Arachis hypogaea L.) growing regions. Chemical control is expensive, sometimes inaccessible, and can be difficult to apply. One effective solution to control this disease is the deployment of resistant cultivars. IAC 322 is a breeding line resistant to foliar fungal disease and harbors alien introgressions from A. cardenasii Krapov. & W.C. Gregory, a wild diploid relative of peanut. The objective of this study was to determine the level of LLS resistance conferred by introgressed segments in families derived from TifNV‐High O/L × IAC 322. Phenotyping for LLS resistance was performed under both in vitro and field conditions, which provided sufficient disease pressure to separate the means of susceptible and resistant checks, although there was no statistically significant separation of LLS resistance among the families with introgressions. However, consistent levels of LLS resistance observed in the family with A02‐top/A03‐bottom segments makes it a valuable resource for peanut breeding. In addition, late‐season field disease ratings were found to correlate with the entire LLS infection progression under both field and in vitro conditions. Among the parameters collected for in vitro experiments, numbers of LLS lesions and sporulating LLS lesions at late stages of LLS infection and incubation period can be used to predict LLS resistance under field conditions.