Inheritance of resistance to the peach root-knot nematode (Meloidogyne floridensis) in interspecific crosses between peach (Prunus persica) and its wild relative (Prunus kansuensis)

The peach root-knot nematode, Meloidogyne floridensis (MF), infects majority of available nematode-resistant peach rootstocks which are mostly derived from peach (Prunus persica) and Chinese wild peach (P.davidiana). Interspecific hybridization of peach with its wild relative, Kansu peach (P.kansuensis), offers potential for broadening the resistance spectrum in standard peach rootstocks. We investigated the inheritance of resistance to MF in segregating populations of peach ('Okinawa' or 'Flordaguard') x P.kansuensis. A total of 379 individuals from 13 F-2 and BC1F1 families were challenged with a pathogenic MF isolate MFGnv14 and were classified as resistant (R) or susceptible (S) based on root galling intensity. Segregation analyses in F-2 progeny revealed the involvement of a major locus with a dominant or recessive allele determining resistance in progeny segregating 3R:1S and 1R:3S, respectively. Testcrosses with a homozygous-susceptible peach genotype ('Flordaguard' or 'UFSharp') confirmed P.kansuensis as a source of new resistance and the heterozygous allelic status of P.kansuensis at the locus conferring resistance to MF. We propose a single-locus dominant/recessive model for the inheritance of resistance.