MOLECULAR GENETIC MARKERS FOR ROOT-KNOT NEMA- TODE RESISTANCE IN SOME PEACH ROOTSTOCKS

Six peach rootstocks were collected according to their susceptibility to infestation of root-knot nematodes; Meloidogyne incognita and M. javanica. These rootstocks were Okinawa, Nemaguard and Nemared (nematode resistant) and Hegazy, Shami and Sultani (nematode  susceptible),  which  screened by randomly amplified polymorphic DNA (RAPD)  markers  using  31  arbitrary  10-mer primers and two SSR primer pairs. Twenty molecular markers related to root-knot nematode have been detected (using 12 primers), 13 of which were negative since they appeared in susceptible root-stocks  and  were  absent  in  the  resistant ones, and seven were positive markers which were present in the resistant root-stocks. Dendrogram tree generated across RAPD  and  SSR  analysis  demonstrated that the highest similarity was scored between Shami and  Sultani (94.1%) while the lowest similarity was scored between Okinawa and Sultani (82.3%). Because of the differences in the rootstocks traits and the molecular genetic diversity of these rootstocks, marker-assisted selection (MAS) in peach rootstocks breeding programs, under biotic stresses (Meloidogyne incognita and M. javanica), is recommended as an efficient tool for improving peach rootstocks resistance.