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

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

Isolation and study of a ubiquitously expressed tomato pectin methylesterase regulatory region

Pectin methylesterase (PME) is an enzyme located in the plant cell wall of higher plants whose physiological role is largely unknown. We had isolated a PME gene from a tomato genomic library, including 2.59 kb of 5üL flanking region and the coding region. Both coding and promoter region were sequenced and computer analyzed. Tobacco transgenic plants were created harboring constructs in which 2.596 Kb, 1.306 Kb and 0.267 Kb sizes of the promoter were driving the expression of âÀ-Glucuronidase gene (GUS). GUS activity was studied by histochemical and fluorometric assays. Two introns of 106 and 1039 bp were found in the coding region and phylogenetic analysis placed this PME gene closer to genes from Citrus sinensis and Arabidopsis thaliana than tomato fruit-specific PME genes. In the promoter, it was found direct repeats, perfect inverted repeats and light responsive elements. GUS histochemical analysis showed activity in all plant tissues with the exception of pollen. The reduction in the promoter size induced a reduction in GUS activity in root, stem and leaf. Furthermore, root and leaf showed the highest and lowest activity, respectively. We had isolated a tomato PME gene with novel characteristics as compared with other known PME genes from tomato.