and it confers resistance to many
populations of M. incognita, M. arenaria, M. hapla, and
M. javanica. Genetic studies have indicated that this locus
may have several alleles including rk, Rk, and Rk2. Rk2
confers broad-based resistance to different races of
M. incognita and M. javanica (Roberts et al., 1996).