Comparison of PCR-based molecular markers for identification of Mi gene.

Tomato (Solanum lycopersicum) is an important horticultural plant in intensive agriculture. Many pests and pathogens affect tomato worldwide. Root-knot nematodes (RKNs) are considered to be one of the most important pathogen groups. Development of resistant tomato varieties to nematode provides an economically and environmentally approach for the management of nematodes. TheMi-1gene confers resistance to RKNs in tomato. Since resistance testing to RKN is time consuming, laborious, and costly, molecular markers linked to the resistance gene have been developed for breeding purposes.Mi-1gene is located on short arm of chromosome 6 and very tightly linked toTy-1gene. The genomic region containingMi-1andTy-1is genetically very short. Therefore, there is problem introgressions of plants bearing bothMi-1andTy-1. Therefore, some markers such as Rex used for screening ofMi-1gene can give false-positive results in plants with some of the begomovirus-resistant germplasm derived from Ih902, which has begomovirus-resistance genes introgressed fromSolanum habrochaites.Although molecular markers tightly linked toMi-1gene have been developed, they have not been applied to a wide range of plants carryingTy-1gene or not carryingTy-1, and compared with each other. In the present study, these markers have been employed in tomato lines and hybrids carryingTy-1gene or not carryingTy-1, and evaluated with each other. A total of 116 tomato plants were tested by markers JB-1, Rex, PMi12, and Mi23. The JB-1 yielded accurate results in all the genotypes tested. Markers Rex, PMi12, and Mi23 gave consistent results in plants that do not haveTy-1gene. PMi12 and Mi23 also produced logical findings for plants carryingTy-1. However, marker Rex-1 produced false-positive results in other samples bearingTy-1gene, except four plants. Our findings showed that both PMi12 and Mi23 markers can be suggested for screening of RKN resistance in tomato-breeding programs. [ABSTRACT FROM PUBLISHER]

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