|Beckman, Thomas - Tom|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2000
Publication Date: N/A
Interpretive Summary: Root-knot nematodes can cause significant economic damage to the peach industry in the southeastern United States if not controlled. Managing some species of this nematode pest has been accomplished through the development of resistant peach rootstocks. However, differing explanations in trying to elucidate the nature of nematode resistance on a genetic level have occurred. Understanding the genetic inheritance is needed to properly evaluate root-knot resistance in rootstocks. Two F1 peach hybrids developed from a cross of Lovell (nematode susceptible) and Nemared (nematode resistant) were selfed to produce F2 seedlings and were evaluated for host susceptibility to 2 root-knot nematode species. Results indicate that resistance to the southern root-knot nematode in Nemared is controlled by two dominant genes and that to the Javanese root-knot nematode by a single shared dominant gene. These data were necessary to provide breeders with a better understanding in evaluating root-knot nematode resistance in current rootstocks and also provide a basis to more efficiently evaluate rootstocks in the future.
Technical Abstract: Two F1 hybrid Prunus rootstocks, K62-68 and P101-41, developed from a cross of Lovell (susceptible to both Meloidogyne incognita and M. javanica) and Nemared (resistant to both root-knot nematode species), were selfed to produce two F2 seedling populations. Vegetative propagation by herbaceous stem cuttings was used to produce 4 to 8 self rooted plants of each F2 seedling for treatment replications. Eggs of M. incognita and M. javanica were inoculated into the potted media where plants were transplanted, and plants were harvested and roots examined for signs and symptoms associated with root-knot nematode infection approximately 120 days later. Segregation ratios in both F2 families suggested that resistance to M. incognita in Nemared is controlled by two dominant genes (Mi and Mij) and that to M. javanica by a single dominant gene (Mij). Thus, Mij conveys resistance to both M. javanica and M. incognita.