Identification and Genetic Evaluation of a New Source of Pod Wart Resistance for Peanut (Arachis hypogaea L.)

Pod wart disease severely damages in-shell peanut (Arachis hypogaea L.) production in areas in which peanut is routinely rotated with potato (Solanum tuberosum L.). It is caused by soil-borne Streptomyces that cause unsightly scabs that render the affected pods unmarketable. Since all elite peanut cultivars are susceptible to pod wart, a new genetic source of resistance is required. Here, the identification and evaluation of a new genetic source of pod wart resistance is reported. The US mini-core peanut collection was evaluated under field conditions, and the least susceptible genotypes were reevaluated in three locations. This led to the identification of two "landrace" genotypes that were significantly resistant to pod wart, with an average of 70% less infection than the control line. Two populations were prepared from crosses between these genotypes and an elite cultivar. Genetic analysis of segregating F-2 populations showed that pod wart tolerance is polygenic with medium heritability estimations. No significant correlation was found between the incidence of pod wart and pod reticulation, indicating that the deep reticulation does not provide resistance. In addition, no significant correlation was found between the incidence of pod wart and pod yield, seed weight, or seed ratio. However, the incidence of disease was positively correlated with pod weight and pod length, indicating genetic linkage or a pleotropic effect on pod wart resistance. This study suggests that pod wart resistance can be selected in early generations of breeding pedigrees, but large populations are needed for optimal pyramiding of other pod- and yield-related traits.