Root-knot nematodes, Meloidogyne spp., cause considerable damage in eggplant production. Transferring of resistance genes from wild relatives would be valuable for the continued improvement of eggplant. Solanum aculeatissimum, a wild relative of eggplant possessing resistance to Meloidogyne incognita, is potentially useful for genetically enhancing eggplant. In the present study, we have isolated and characterized a nucleotide-binding site leucine-rich repeat (NBS-LRR) resistance gene, designated as SacMi. The full-length cDNA of the SacMi gene was obtained using the technique of rapid-amplification of cDNA ends (RACE). The open reading frame of the SacMi gene was 4014 bp and encoded a protein of 1338 amino acids. Sequence analysis indicated that SacMi belong to the non- Toll/Interleukin-1 receptor (TIR)-NBS-LRR type disease-resistance genes. Interestingly, quantitative RT-PCR showed that SacMi is expressed at low levels in uninfected roots, but was up-regulated by infection with M. incognita. To investigate the role of SacMi in S. aculeatissimum resistance against M. incognica, the tobacco rattle virus (TRV)-mediated virus-induced gene silencing (VIGS) system was used. Silencing of SacMi enhanced susceptibility of S. aculeatissimum plants to M. incognita, suggesting the possible involvement of SacMi in resistance against M. incognita infection.
Keywords: Solanum aculeatissimum; resistance; root-knot nematode; virus-induced gene silencing.