Resistance Response of the Commercial Tomato Cultivars and Rootstocks Carrying Mi-1.2 Gene to (A)virulent Isolates of Meloidogyne luci

Abstract

Meloidogyne luci is a polyphagous root-knot nematode species having high reproductive potential and represents a significant threat to global tomato production. The Mi-1.2 gene in tomato confers resistance to M. luci. However, nematode population and plant genetic background may influence the resistance mediated by this gene. The study was conducted to identify the allelic condition of the Mi-1.2 gene in seven tomato cultivars and seven tomato rootstocks and to determine the reaction of these plant genotypes to Mi-1.2 (a)virulent isolates of M. luci under controlled conditions. All tomato rootstocks and one cultivar were identified as homozygous resistant form (MiMi), whereas other tomato cultivars were heterozygous resistant (Mimi) at the Mi gene locus. All rootstocks and cultivars with Mi-1.2 gene were highly resistant to the avirulent isolate of M. luci, with the exception of the King Kong RZ rootstock which showed a moderate level of resistance. However, these plant genotypes supported the reproduction of the virulent M. luci isolate and exhibited reduced resistance. The homozygous resistant cultivar Browny was more resistant than others, showing moderate resistance to the virulent isolate of M. luci. The rootstocks Arazi, Arbiore, Embajador and Interpro responded as slightly resistant, while the remaining rootstocks and cultivars were classified as susceptible. Within each Mi allelic condition significant differences in reproduction of virulent M. luci isolate were detected, indicating that genetic background may be effective in resistance.