Development of Near‐Isogenic Peanut Lines with and without Resistance to the Peanut Root‐Knot Nematode

Peanut ( Arachis hypogaea L.) cultivars are available that have high resistance to the peanut root‐knot nematode [ Meloidogyne arenaria (Neal) Chitwood race 1] or tomato spotted wilt, caused by tomato spotted wilt Tospovirus (TSWV); however, no cultivars exist that have resistance to both pathogens. The objective of this research was to combine resistance to both pathogens in a single genotype. During the course of this research, we also had the opportunity to develop near‐isogenic lines with and without nematode resistance. Such near‐isogenic lines can be valuable research tools to obtain a better understanding of the interaction of nematodes with other pathogens of peanut. Breeding populations were developed by hybridizing the TSWV‐resistant cultivar C‐99R with the nematode‐resistant cultivar COAN. Selection for nematode resistance was conducted using standard greenhouse screening techniques. Selection for TSWV resistance was conducted in the field with natural virus infection. A breeding line (C724‐19‐15) was selected that had high resistance to both pathogens. A near‐isogenic line (C724‐19‐25) susceptible to the peanut root‐knot nematode was also developed. Both breeding lines exhibited higher resistance to TSWV and higher yield than standard check cultivars when grown in fields with little or no nematode pressure.