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Background: Root-knot nematodes (RKN, Meloidogyne spp.) are harmful phytophagous pests of Solanum spp. Some RKN species are becoming worldwide problems because of their virulence to RKN-resistant Solanum species. A new Solanum species carrying broad-spectrum resistance to Meloidogyne spp. is required for the effective management of this pest. Here we sought to determine the host suitability of RKN to Solanum palinacanthum, a wild Solanum species, and to evaluate its potential effectiveness in RKN management., Results: We identified an RKN-resistant Solanum species, S. palinacanthum, by screening Solanum accessions. We tested its spectrum of resistance to common Meloidogyne spp. in Japan. In pot tests inoculated with second-stage juveniles, S. palinacanthum showed poor host suitability for Melidogyne incognita, M. arenaria genotypes A2-J and A2-O, M. javanica and M. hapla, indicating broad-spectrum resistance to RKN. The development of M. incognita within S. palinacanthum roots was significantly poorer than that in susceptible S. melongena and S. lycopersicum at 10 and 21 days after inoculation. Microplot tests confirmed that the number of second-stage juveniles in plots where S. palinacanthum grew and root galling of the root system were significantly lower than those of susceptible S. melongena, suggesting that the resistance could be used to manage RKN under field conditions., Conclusion: S. palinacanthum showed poor host suitability to all Meloidogyne spp. tested in this study, and it thus has the potential to be used as a genetic resource with broad-spectrum RKN resistance, and it could be effective against multiple RKN species in a field. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)

Eggplant (Solanum melongena) is susceptible to root‐knot nematodes (RKN, Meloidogyne spp.), which parasitizes host roots and intakes nutrients from nursing cells called 'giant cells'. Grafting with RKN‐resistant rootstock is an effective way to reduce the damage caused by RKN. However, commercially available cultivars of RKN‐resistant rootstock for eggplant are limited, and resistance in RKN‐resistant plants is sometimes ineffective. A wild eggplant relative, Solanum palinacanthum, was recently found to be resistant against a wide range of Meloidogyne spp. In this study, we assessed the suitability of S. palinacanthum as an eggplant rootstock. First, we checked the grafting compatibility of S. palinacanthum rootstock to scions of commercial cultivars of eggplant. The scions of the eggplants and the rootstock of S. palinacanthum united well, and the grafted plants grew stably, whereas S. palinacanthum was seemingly incompatible with tomato. The grafting of eggplants on S. palinacanthum rootstock significantly suppressed the reproduction of Meloidogyne incognita in a pot experiment. The grafted plants also reduced the population densities of RKN infesting the experimental fields, whereas the grafting did not significantly change the yields. In addition, we measured the contents of representative alkaloids in the fruits of the grafted eggplant, which can be toxic if consumed in large amounts. The results show that the grafting did not make any difference in the contents of α‐solasonine and α‐solamargine in the fruit. These results support that S. palinacanthum is a promising eggplant rootstock for Integrated Pest Management (IPM) against RKNs. [ABSTRACT FROM AUTHOR]

Solanum torvum, a wild Solanum species, is widely used as a rootstock and is known for its resistance to several pathogens and pests including root‐knot nematode (RKN, Meloidogyne spp.). Virulence to S. torvum was observed in several Meloidogyne species such as M. hapla, but M. hapla populations isolated from Japan have not been tested for parasitism. We performed inoculation assays on S. torvum cultivars and control plants (S. melongena, eggplant; S. lycopersicum, tomato) inoculated with Japanese M. hapla populations, and we then evaluated the host suitability based on the eggmass number. The assays were carried out using nursery plants in small plastic pots. The first assay revealed that S. torvum cultivars that are commercially available in Japan were susceptible to M. hapla. In the second assay, three M. hapla populations obtained from geographically distant areas produced a number of eggmasses on S. torvum roots. The S. torvum cultivars were all resistant to M. incognita, as a control species of Meloidogyne, in both assays. Our examination of the number of eggs per eggmass of M. hapla demonstrated that the values of S. torvum under inoculation of two M. hapla populations were significantly lower than those of S. lycopersicum, implying some difference in the fecundity of M. hapla depending on the host plants. The series of experiments revealed the virulence and reproductivity of Japanese M. hapla populations to S. torvum, posing a potential risk that S. torvum cannot suppress RKN damage in agricultural fields under infestation of such Meloidogyne species. [ABSTRACT FROM AUTHOR]