Pathogenicity of Meloidogyne incognita and M. javanica on recombinant inbred lines from a crossing of Cucurbita pepo subsp. pepo × C. pepo subsp. ovifera

The response of recombinant inbred lines ( RIL s) from a cross of zucchini × scallop ( Cucurbita pepo subsp. pepo ‘Murcia MU ‐ CU ‐16’ ×  C. pepo subsp. ovifera ‘Scallop UPV ‐196’) to Meloidogyne incognita and M. javanica was determined after completion of a nematode reproduction cycle in experiments carried out in a growth chamber. The nematode differentiated the C. pepo genotypes at the subspecies level due to lower egg mass production on subspecies pepo than ovifera , and thus subspecies pepo was a poorer host than ovifera . In addition, Murcia MU ‐ CU ‐16 discriminated M. incognita from M. javanica in terms of egg masses ( EM ), eggs per gram of root and reproduction factor (Rf), whereas Scallop UPV ‐196 did so in eggs per gram of root and Rf. The RIL s differed in gall formation and EM production depending on the nematode × line combination. Comparisons between nematode isolates resulted in four significant combinations for pathogenic potential (galls/initial population (Pi) × 100), seven for parasitic success (egg masses/Pi × 100), and nine for host efficiency (egg masses/galls per root system × 100) which included all the lines tested against both isolates. Lines that restricted nematode development by at least 90% were considered as having intermediate resistance to M. incognita based on the definition of the International Seed Federation. They included lines 28‐1, 35A, 107A, 110‐3 and 153‐2. All the RIL s were susceptible hosts for M. javanica . The information presented here will be helpful for nematode management and also for plant breeders working on pathogen resistance on C. pepo .