4.1. Plant Material and Nematode Infection

Seeds of Solanum torvum Sw accession TG1 (RKN-resistant) and eggplant (Solanum melongena L., RKN-susceptible) breeding line Sme were sown in a seed plot for germination according to Gousset et al. (2005) [39]. Seedlings at the fifth-leaf stage were transplanted into 15 cm diameter plastic pots, with 500 cc of a mixture of sterilized sandy soil [40]. The pots were maintained in controlled chambers at 28 °C, 70% humidity, with a 14 h light/10 h dark. Then, the resistant (torvum (Tor)) and susceptible (Sme) lines were inoculated at the base of the plant stem with hatched root-knot nematode (Meloidogyne incognita, RKN) at the second larval stage (J2). RKNs were maintained in the greenhouse on eggplant; eggs masses were extracted as described by Shukla et al. (2018) [19]. For transcriptome study, the Sme and Tor lines were sampled at the uninfected stage (CK) and 7, 14, and 28 days post-infection (dpi) in the susceptible response. The soil was removed from the root tissues collected from each type of plant, the plants were washed with water and then frozen in liquid nitrogen to prevent RNA degradation. Finally, root samples were stored at –80 °C until RNA isolation.