Inheritance of Resistance to Peach Root-knot Nematode (Meloidogyne floridensis) in Interspecific Populations of Peach

We examined several F₂ and BC₁F₁ populations that were generated from interspecific crosses between Prunus kansuensis Rehder (Kansu peach) and Prunus persica (L.) Batsch (peach) for segregation of resistance to the peach root-knot nematode (RKN), Meloidogyne floridensis (MF). The segregation analyses were based on fourteen different populations with P. kansuensis as the common male parent and each population comprised of forty individual genotypes. Eight F₂ populations were generated from self-fertilization of ‘Okinawa’ peach or ‘Flordaguard’ peach x P. kansuensis hybrids. Six BC₁F₁ populations were from 'Okinawa' x P. kansuensis or ‘Flordaguard’ x P. kansuensis hybrids backcrossed to ‘UFSharp’ peach, which has a known susceptibility to RKN, or to ‘Flordaguard’ peach, which expresses a certain degree of RKN resistance. Response to MF was evaluated by inoculating with a single MF population isolated from peach in Florida. The individuals were classified as resistant or susceptible based on the amount of galls and egg masses per gram of fresh root. Preliminary data showed two different segregation ratios among the six ‘Okinawa’ x P. kansuensis F₂ populations while most of the peach x (peach x P. kansuensis) populations seemed to fit a 1:1 segregation. The observed segregation ratios appear to support the presence of a single dominant locus in P. kansuensis that confers resistance to MF.