Tfg-Mi, a root-knot nematode resistance gene from fenugreek [Trigonella foenum-graecum] confers nematode resistance in tomato

ABSTRACT

Several root-knot nematode [Meloidogyne spp.] resistance genes have been discovered in different plants. For the first time, the Mi gene from fenugreek [Trigonella foenum-graecum] was detected in this study. A candidate root-knot nematode resistance gene [designated as Tfg-Mi] was isolated from the resistant fenugreek line Giza 3 by degenerate PCR amplification combined with the RACE technique. Also, another two candidate root-knot nematode resistance genes [designated as To-Mi11 and To-Mi12] were isolated from the resistant tomato [Lycopersicon esculentum] line Nemagard. Expression profiling analysis revealed that both genes were highly expressed in roots, leaves and flowers and expressed at a lower level in stems, but are not detectable in fruits. To verify the function of Tfg-Mi, a sense vector containing the genomic DNA spanning the full coding region of Tfg-Mi was constructed and transferred into root-knot nematode susceptible tomato plants. Sixteen transgenic plants carrying one to five copies of T-DNA inserts were generated from two nematode susceptible tomato cultivars. RT-PCR analysis revealed that the expression levels of Tfg- Mi gene varied in different transgenic plants. PCR assays showed that the resistance to root-knot nematodes was significantly improved in some transgenic lines compared to untransformed susceptible plants, and that the resistance was heritable