Growth and resistance response of eleven eggplant cultivars to infection by the Javanese root-knot nematode - Meloidogyne javanica under greenhouse conditions

In Saudi Arabia, root-knot nematodes (RKNs) were found to cause considerable damage to eggplant. These parasites cause significant death of seedlings during nursery production, with infected plants showing the symptoms of chlorosis and wilting, along with the characteristic root galls. Therefore, this work was carried out to find a resistant cultivar of eggplant against RKNs in Saudi Arabia by screening 11 locally available cultivars for two successive seasons. Following Koch's postulates for pathogenicity, RKNs were isolated from infected eggplant, and females were identified morphologically by perineal patterns as Meloidogyne javanica, which was distinguished by clear lateral fields on both sides. Identification was confirmed using two species-specific primers (SCAR), Fjav/Rjav and MjF/MjR, and visualized amplified fragments appeared at 670 bp and 517 bp, respectively. A greenhouse experiment was conducted to screen the cultivars, using five replicates for each cultivar and nematode inoculum (1 000 second-stage juveniles). In response to M. javanica, gall index (GI), egg mass index (EMI), and reproduction factors (RF) were calculated, and all the eggplant cultivars were categorized according to their resistance levels based on RF. Among the 11 eggplant cultivars, four were found resistant to M. javanica including Black Beauty (C5, Bursa Tohum), Melanzana Violetta Difirenze (C6, Zorzi), Melanzana Violetta Lung 2 (C7, Zorzi), and Long Purple (C9, Bursa Tohum) and Violetta Lung 3 (C8, Taj Agri) was found highly resistant. Moreover, two cultivars were found moderately resistant, two susceptible, and two susceptible to M. javanica infection. Therefore, this study provided valuable information to eggplant growers about the resistant cultivars in Saudi Arabia. However, the molecular mechanisms of this resistance need to be evaluated to find novel candidate genes for breeding and CRISPR-Cas9-based gene editing programs.